Synology RS4021xs Synology MailPlus Server Administrator s Guide - Based on Ma
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- Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 1
Administrator's Guide for Synology MailPlus Server Based on Synology MailPlus Server 2.3 1 - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 2
Multiple I/O Intensive Packages on the Same NAS Chapter 2: Getting Started with MailPlus Server 06 Connect Synology NAS to the Internet Set up DNS Set up MailPlus Server Set up MailPlus Client Run MailPlus Third-Party Email Clients Troubleshoot Chapter 3: Mail Migration 19 Create a Mail - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 3
Chapter 6: Protocol Settings 47 SMTP IMAP/POP3 Network Interface Chapter 7: SMTP Settings 51 Service Settings SMTP Secure Connection Mail Relay Chapter 8: Domain Settings 67 Domain Domain Management Chapter 9: Security Settings 84 Antispam Antivirus Scan Authentication - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 4
Introduction Introduction The Synology MailPlus suite provides advanced and secure mail service with high usability. This suite This administrator's guide will guide you through the MailPlus Server setup and give detailed configuration instructions including DNS settings, mail service migration, - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 5
guide on best practices to follow when deploying MailPlus to ensure the stability and performance of mail services. The following is discussed below: how to select a Synology NAS process per day. 2. Visit Synology product page to find a list of every model that supports MailPlus. By clicking on the - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 6
Concurrent Users as specified by the specifications of the model of Synology NAS, sudden spikes in memory usage may occur as MailPlus Server person is 100 per day, and a mail service usually lasts for three to five years. For example, if your MailPlus supports 200 users, the required storage size is: - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 7
cache. Installing an additional SSD and utilizing Synology SSD cache will enhance the overall performance of the mail service. Note: • It is essential that enterprise and power loss protection. Synology SSDs are enterprise-class SSDs that are built for 24/7 NAS environments and are verified through - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 8
more than meets the minimal requirements. The following guide provides a quick SSD cache size estimation based on services, a Synology NAS is capable of running multiple services at the same time. For example, MailPlus Server and Synology Drive should not be installed on the same NAS, but Synology - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 9
with MailPlus Server With MailPlus Server, a Synology NAS can serve as a mail system that supports SMTP, POP3, and IMAP. User accounts and email messages can be centrally managed and archived on a Synology NAS. MailPlus, as a client package, provides mail service users with an easy-to-use and - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 10
Protocol (SMTP). Each MX record contains a hostname and a preference. A hostname guides emails to arrive at the right mail server. A preference points out the example.com, and the host server is the Synology NAS on which MailPlus Server is running. From Hostname mail.example.com To IP Address - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 11
are for demonstration purposes only. The DNS record interface that each provider offers may vary. If you have problems configuring DNS records, please contact your domain providers. Reverse DNS setup The process of assigning specific DNS records to a domain name is known as forward DNS. This is what - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 12
Chapter 2: Getting Started with MailPlus Server How to set up reverse DNS? • Set up reverse DNS on your own host: Some ISPs may delegate a portion of the zone to users so that users can host their own reverse DNS. You can configure reverse DNS by determining PTR records in a DNS server. PTR records - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 13
2. Launch MailPlus Server and select Create a new mail system if you want to set up a whole new mail system, and click Next to continue the setup. Otherwise, you can select Create a new mail system by migrating the data from previously installed Mail Server. Check this tutorial to see how to migrate - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 14
domain users) that will be allowed to use MailPlus services. • Network interface: Select a LAN port used for will be stored. 5. Click Next to check the setup summary and click Apply to finish the settings. 6. folder will be automatically added to the Synology NAS. To ensure client users can access - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 15
a web-based interface for client users to access and manage emails hosted on a Synology NAS. Multiple POP3 accounts can be created in MailPlus, allowing users to fetch messages via other mail service providers (e.g., Mozilla® Thunderbird®, Gmail, and Office 365). Install MailPlus 1. Go to Package - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 16
: • Go to Main Menu > MailPlus. • Access MailPlus via Application Portal. Enter the name of the Synology NAS followed by "/mail" in the address bar of your web browser. For example, if the Synology NAS is called mydiskstation, enter mydiskstation/mail. Please refer to this help article to see how to - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 17
2. Enter your DSM username and password to sign in. Chapter 2: Getting Started with MailPlus Server 3. If the settings of MailPlus Server have been configured before the installation of MailPlus, the SMTP settings of MailPlus Server will automatically appear at Settings > SMTP. 14 - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 18
® Thunderbird®. In the example below, we'll show you how to use Thunderbird® to access an email account hosted on a Synology NAS. 1. Launch MailPlus Server and go to the Service page to enable IMAP and POP3. 2. Launch Thunderbird® on your computer and click Email to launch the Set up an Existing - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 19
Server 3. Enter the name, MailPlus address, and password for your DSM user account. Click Continue. 4. Thunderbird® will search for your MailPlus account. If the settings are correct, click Done to finish the settings. 5. Once the setup is complete, your MailPlus account will appear on the left - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 20
Chapter 2: Getting Started with MailPlus Server Troubleshoot Why can't I send or receive emails via webmail from MailPlus? 1. Check if settings on your MailPlus such as SMTP, DNS, and MX are correct. 2. Check if the Internet settings of the Synology NAS are correct. Go to Control Panel > Regional - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 21
Make sure DNS settings are correctly configured. You will need to point the MX and A records to the Synology NAS so that other mail servers can find the Synology NAS. 2. Make sure the Synology NAS has a static IP address and is connected to the Internet, or your domain name points correctly to your - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 22
without complicated setup. This chapter will guide you through how to migrate emails from Microsoft Exchange to MailPlus Server. Before you start, please make sure you have done the following: • Check if the Synology NAS is running DSM 6.0 or later and supports MailPlus Server (see compatible models - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 23
Chapter 3: Mail Migration 2. Go to the General tab in the Migration Settings window, set Select the server type to Microsoft Exchange, and fill in the required information of the Microsoft Exchange server. 3. The IMAP path prefix can be found within the settings of your Microsoft Exchange server. 4. - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 24
Chapter 3: Mail Migration Import a user list 1. Prepare a user list following the requirements below: • Generate a user list in CSV format using a text editor. • List one user account information in one row. • List each user's following information from left to right: the source account, the source - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 25
Set up email and mailbox filters 1. At the Filter tab, specify criteria to migrate or skip certain emails and mailboxes. Chapter 3: Mail Migration 2. To filter mailboxes with keywords, tick the Enable mailbox filter checkbox and select a filter policy (Skip mailboxes by keyword or Migrate - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 26
Chapter 3: Mail Migration Set up migration notifications 1. Make sure Enable SMTP (at Service) is ticked in MailPlus Server to allow notification delivery. 2. At the Notification tab, determine whether MailPlus Server should send notifications about each account's migration results - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 27
Run a mail migration task 1. At Server Management > Mail Migration, you can select a migration task and click Start to run it. To avoid migration errors, do not change IMAP/POP3 settings in MailPlus Server or move/delete emails on the source mail server. Chapter 3: Mail Migration 2. Click - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 28
Exchange server and have them imported to MailPlus Server for continuous use. Export system configurations and aliases from Microsoft Exchange 1. Download the script file (ExchangeConfigExport.ps1) from here. 2. Log in as the system administrator to a Windows computer running the Microsoft Exchange - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 29
Import system configurations to MailPlus Server 1. Begin the import process in either way below: • When MailPlus Server is to be initialized: Launch MailPlus Server and select Create a new mail system by importing configurations from Microsoft Exchange. • When MailPlus Server has already been - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 30
multiple domains, so using multiple domains does not require additional licenses. • DSM users that do not belong to the specified account type: For example, or 20 units of email accounts and can be purchased through Synology authorized resellers. For details on MailPlus license packs, please refer - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 31
window, please carefully read the license agreement for MailPlus Server. After checking and confirming the content, click Agree. 3. Sign in to the Synology Account and click Next. Note: • Should there be situations where licenses are unable to be retrieved after being activated, sign in to the - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 32
Chapter 4: User Licenses 4. Enter the license number in the License Key field as shown in the image below. If you need to add more than one license, click on the plus icon (+) to add more fields. 5. Check and confirm if the number of licenses to be installed and their respective license keys are - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 33
the number of used and unused licenses. User Licenses After adding licenses, you can go Account > User to choose which accounts to activate. For detailed instructions, please refer to Activate Accounts. 30 - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 34
LDAP, or Domain. Modify account type Please follow the steps below to modify account type: 1. Sign in to your DSM. 2. Go to Control Panel > Domain/LDAP to bind with a specific directory service. If you are using Local users as the account type, please skip this step. 3. Launch MailPlus Server. 4. Go - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 35
Settings 5. Click Apply to import user accounts from the directory service. As shown in the following image, if you switch from Local click Yes. The system will only migrate emails to directory service accounts with the same usernames as local users. Accounts with different usernames will be automatically ignored - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 36
Activating user accounts requires a sufficient number of licenses. For more instructions, please refer to User Licenses section. Please follow the steps displays the following DSM user statuses: Normal, Deactivated, and Username unsupported. Note: • Users can use mail services properly only when - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 37
Chapter 5: Account Settings 5. Customize mailbox storage by selecting the target user and click Set Quota to configure the following settings: • MailPlus quota: Specify the mailbox size limit. • Remaining capacity notification: Specify the warning threshold to remind users that their mailboxes are - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 38
Chapter 5: Account Settings 2. Customize mailbox storage quota for groups. Select the target group and click Set Quota to configure the following settings: • MailPlus quota: Specify the mailbox size limit. • Remaining capacity notification: Specify the warning threshold to remind users that their - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 39
Chapter 5: Account Settings 2. Click Apply to save the settings. Create user policies After activating users or groups, you can create dedicated mail service policies for certain users or groups to meet an organization's requirements. Please refer to the following steps to create user policies: 1. - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 40
Chapter 5: Account Settings Note: • For details on policy information, please refer to Policy information and restrictions. 5. Switch to the Target User tab and select a user or group to apply the policy to. You can also use the search bar at the top of the window to find the target. 6. Click OK to - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 41
Chapter 5: Account Settings Change user policy priority Multiple user policies may be applied to one user; however, only one policy will take effect. Which policy will take effect depends on the priority settings of user policies. Please refer to the following steps to change the priority of a user - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 42
Chapter 5: Account Settings 4. Hover to the left of the policy and drag and drop it to a suitable position according to your desired order. 5. Click the two-way arrow icon to close the drag and drop function and make the new priority order take effect. Note: • Default policy will always have the - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 43
Chapter 5: Account Settings Default policies The system default policy will be applied to users that are not regulated by any custom policy. The default policy is a pre-existing policy that cannot be edited, deleted, or re-prioritized. Please refer to the following setting details of the default - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 44
. Results of Disabling Policy Users can autoforward emails. By Domain Policies will follow domain settings. Note: • This policy does not affect manual forwarding. No. Policy 02 Daily sending quota (number) Results of Enabling Policy Users will be restricted by a quota. Results of Disabling - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 45
Disabling Policy Users will be restricted from using IMAP. Note: • If the Enable IMAP checkbox under the IMAP/POP3 section in the Service page is not ticked, IMAP services will not be available and the user policy will not take effect. Users will not be able to use IMAP even when IMAP - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 46
The server will not index email content of users. Note: • If the Enable full-text search checkbox under the Full-Text Search section in the Service page is not ticked, the user policy will not take effect, and the email content of users will not be indexed. Create delegation policies At - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 47
Chapter 5: Account Settings 2. In the pop-up window, go to the Delegation tab and enter the required information. The system will automatically tick the options below based on the selected delegation profile. The profile will switch to Custom when you tick or untick any options below. Please refer - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 48
Chapter 5: Account Settings 3. Go to the Target User tab to select the users/groups to be regulated under the defined delegation policy. 4. Click OK to save the settings. Manage delegation policies 1. Go to Account > Delegation. 2. Select Domain Admin to view, edit, and delete a policy. 3. You can - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 49
Chapter 5: Account Settings Manage Privileges MailPlus Server privilege settings are synchronized with DSM settings. Users who are from the administration group on DSM can access all the MailPlus Server settings, while general users can only see the Personal page (as shown in the image below). Note: - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 50
here. • SMTP-SSL: SMTPS is a supported protocol for SMTP-SSL. Since DSM no longer supports SSL encryption, MailPlus Server can only connect Set up SMTP Please refer to the following instructions on the configuration of SMTP and respective ports: 1. Go to Service > Protocol > SMTP and tick the Enable - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 51
protocols, you can retrieve email information from MailPlus Server using different email clients. Note: • Both protocols encrypt through STARTTLS. Since DSM no longer supports SSL encrypted connection, please do not set up SSL for an encrypted connection. • IMAP: IMAP is a standard protocol that - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 52
allows users to access data stored on a mail server. POP3 clients download emails from the server and save them locally, so changes made following steps to configure IMAP, POP3, and their respective ports: 1. Go to Service > IMAP/POP3. 2. You can adjust the following settings under the IMAP/POP3 - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 53
a network interface to support High-availability cluster. The mail service hosted on the server LAN or a bonded network interface. You can use manual configuration to retrieve the IP address of the network 1. Sign in to DSM. 2. Launch MailPlus Server. 3. Go to Service > Network Interface and - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 54
You can go to the Mail Delivery page to set up rules for sending and receiving emails. MailPlus Server provides quick and convenient service setting options including the following: • SMTP profile: You can specify a hostname for MailPlus Server and an SMTP banner on a client's Telnet terminal. In - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 55
Chapter 7: SMTP Settings 2. Click Apply to save the settings. External postmaster External postmaster is set to receive system emails sent to Mailer-daemon and Postmaster aliases from other mail servers. 1. Go to Mail Delivery > General. 2. Click the External Postmaster button. 3. Tick the Enable - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 56
client users to conveniently search keywords on clients supporting this feature (e.g., MailPlus). Note: • Enabling a large number of outbound and inbound messages. 1. Go to Service. 2. Under the Full-Text Search section, you can adjust the need to enter their DSM user accounts and passwords for authentication - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 57
you can adjust the following settings: • Skip authentication for local network connections from terminal: Users who use the local network to access mail services do not require authentication. • Check if the sender's email addresses belong to the login accounts: Users have to use the email addresses - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 58
Chapter 7: SMTP Settings 3. Click Apply to save the settings. Create blacklist & whitelist The system will take specific actions on certain messages based on various criteria specified in Blacklist & Whitelist. You can refer to the following steps to create rules for blacklist and white list: Note: - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 59
4. Name the blacklist (whitelist) rule in the Name field. 5. Choose a type of rule: • Sender: Takes specific actions when a sender address matches the specified criteria. • Recipient: Takes specific actions when a recipient address matches the specified criteria. • IP: Takes specific actions when a - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 60
Chapter 7: SMTP Settings 8. Click OK to complete the settings. Edit and delete blacklist & whitelist 1. You can enter keywords in the search field in the upper-right corner of the Black & White List window to search for the blacklist or whitelist you want to modify. 2. You can tick the Enabled - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 61
these tests will fail to be delivered. For example, when the sender [email protected] is on the whitelist, since the sender rule does not support DNSBL, DKIM, and DMARC, it must pass DNSBL, DKIM, or DMARC tests to avoid delivery failure. • If you wish to skip all the tests listed - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 62
Chapter 7: SMTP Settings Connection policy 1. Go to Mail Delivery > Security. 2. Under the Connection Policy section, set up the criteria to restrict client connections or block suspicious IP addresses. The policies include the following: • Reject unknown client hostnames: When an IP address or a - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 63
• Reject unknown HELO hostnames: Rejects connection when hostnames do not have DNS A record or MX record during HELO or EHLO. • Block any IP emailing more non-existent accounts than the limit: Blocks the IP address of a user until the next day when the user using the same IP address on the same day - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 64
Chapter 7: SMTP Settings • Always use a secure connection (TLS): MailPlus Server sends STARTTLS to enable encrypted connections. If MailPlus Server is the relay server, please refer to here. In MailPlus Server, the default TLS security level is may. • Authentication required: If your relay server - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 65
• Recipient Rule: Emails sent to the specified email addresses or domains will be sent through a designated relay server. The priority of recipient rules will be higher than that of sender rules. • Sender Rule: Emails sent from the specified addresses or domains will be sent through a designated - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 66
Chapter 7: SMTP Settings Set up relay control At the Relay Control tab, you can adjust MailPlus Server settings, so it can send or receive emails for multiple mail servers. • Relay outbound emails for other mail servers: 1. Go to Mail Delivery > Relay Control. 2. Click the Trusted List button under - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 67
Chapter 7: SMTP Settings 3. Set up an internal Synology DNS Server for MailPlus Server to find your primary mail server. 4. Enter your domain name in the MX record on the internal DNS server and - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 68
Chapter 7: SMTP Settings 5. Go to DSM > Control Panel > Network > General and tick the Manually configure DNS server checkbox. Enter the IP address of the internal DNS server in the Preferred DNS Server field and the IP address of the - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 69
6. Launch MailPlus Server and go to Mail Delivery > Relay Control. Under the Relay Inbound Mails section, click the Domain List button. Chapter 7: SMTP Settings 7. Click the Create button. 8. Enter the rule name and domain. 9. Click OK to save the settings. Note: • Although emails are sent - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 70
Go to Domain and click the Add button. 2. Fill in the domain name synology.456 and its description. 3. When adding members to the domain, MailPlus Server will Custom according to the account type you set at Service > SMTP > Account type. Note: • Editing account names will not change the existing - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 71
select Custom to enter variables in the Custom variables field as the default email address formats. The following table shows the variables that MailPlus Server supports: 68 - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 72
name will be used. You can also enter a variable supported by your account system to fetch the corresponding value. The variables supported by MailPlus Server vary according to the selected account system at Service > SMTP. For more details, please refer to the following table - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 73
Chapter 8: Domain Settings 6. After the setup, click Next. 7. Add users to this domain and click Next to check the members in synology.456. 8. Click Apply to save the settings. 70 - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 74
. Edit general settings for a domain At the General tab, you can edit domain information, adjust default email address format, and add new users automatically to synology.456. Chapter 8: Domain Settings 71 - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 75
recipient. 4. Click Finish to save the settings. Note: • MX records on DNS Server may require relevant adjustments. Adjust advanced settings 1. Go to Domain > synology.456 > Edit > General and click the Advanced button. 2. In the pop-up Advanced window, you can adjust the settings of DKIM and Catch - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 76
• DKIM: You can enable DKIM signing to prevent messages from being modified and also avoid identity theft. a. Under the DKIM section, tick the Enable DKIM signing on outbound emails checkbox if you want to prevent identity theft and make recipients trust your delivered messages. You can adjust the - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 77
enabled in the domain. Add user accounts to a domain 1. Go to Domain, select synology.456, and click Edit. 2. Go to the User tab and click Add. 3. of the selected users. Edit and remove user accounts 1. Go to Domain, select synology.456, and click Edit. 2. At the User tab, select an account and click - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 78
4. If you want to remove a user account, select the target user account and click the Delete button. Add groups to a domain 1. Go to Domain, select synology.456, and click Edit. 2. Go to the Group tab and click Add. 3. Select user groups and click Next. 4. Confirm the email addresses of the members - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 79
to send emails to multiple recipients using one alias. 1. Go to Domain, select synology.456, and click Edit. 2. Go to Alias and click the Create button. 3. following steps to edit or delete an alias: 1. Go to Domain, select synology.456, and click Edit. 2. Go to Alias and select the alias you want - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 80
imported or updated. • Export aliases: Alias files will be exported and downloaded in the Postfix format. Chapter 8: Domain Settings Create Auto BCC rules following steps to create an Auto BCC rule: 1. Go to Domain, select synology.456, and click Edit. 2. Go to Auto BCC and click the Create button - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 81
the following steps to edit or delete Auto BCC rules: 1. Go to Domain, select synology.456, and click Edit. 2. Go to Auto BCC and select the Auto BCC rule steps to import or export Auto BCC rules: 1. Go to Domain, select synology.456, and click Edit. 2. Go to Auto BCC and click the Tools button. 3. - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 82
to always bcc. • Please make sure the imported files are in the Postfix format. Set up sending limit and daily quota 1. Go to Domain, select synology.456, and click Edit. 2. Go to the Usage Limit tab. 3. Under the Sending Limit section, adjust the following settings: • Maximum size per email (MB - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 83
messages here. If a user has reached the daily quota, you can clear records to allow the user to continue sending emails. 1. Go to Domain, select synology.456, and click Edit. 2. Go to the Usage Limit tab and click the Outbound Usage button. 3. Select a specific user from the list. You can also - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 84
one disclaimer can be applied to one email. 1. Go to Domain, select synology.456, and click Edit. 2. Go to the Disclaimer tab and click the Create to append the disclaimer based on Recipient or Sender. The settings support wildcard characters (*). • Exception rule takes priority over Matching rules. - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 85
to bottom. When the criteria for a disclaimer have been met, the disclaimer will be applied, thereby ending the check. 1. Go to Domain, select synology.456, and click Edit. 2. Go to the Disclaimer tab. Higher disclaimers have priority over lower ones. To change their priority, select a desired one - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 86
5. Click Save to apply the settings. Chapter 8: Domain Settings 83 - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 87
mechanisms, MailPlus Server can block spam messages according to your needs. • Postscreen: Reduces the probability of receiving spam by rejecting services for spam servers according to open blacklists and the characteristics of senders from spam servers. • Greylist: Takes actions based on the - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 88
update antispam rules: Tick this option to set up an update schedule, and the system will download the latest antispam rules from the official SpamAssassin website on schedule. • Manual Update: Click the button to update antispam rules immediately. The Engine Information section above the button - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 89
Chapter 9: Security Settings Spam control settings The antispam feature provides various customizable settings. You can adjust the antispam engine according to your needs. Please refer to the following steps to edit spam control settings: 1. Go to Security > AntiSpam to adjust the following settings - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 90
Chapter 9: Security Settings 3. Messages will be marked as spam or non-spam based on the sender and recipient criteria. Wildcard characters (*) can be used in the entered addresses. 4. From the Do this drop-down menu, select Mark as spam or Mark as non-spam. Note: • The spam score will be ignored - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 91
Chapter 9: Security Settings Advanced antispam rules SpamAssassin rules 1. Go to Security > Antispam and click the Advanced button. 2. Go to the General tab in the Advanced window and click the SpamAssassin Rules button. 3. Click the Import button to add SpamAssassin rules. Note: • Imported files - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 92
5. Click Finish to complete the settings. Keyword Filter 1. Go to Security > Antispam and click the Advanced button. 2. Go to the General tab in the Advanced window and click the Keyword Filter button. 3. Click the Group setting button to create a group. You can set up multiple groups to categorize - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 93
Chapter 9: Security Settings Note: • An email will be marked as spam if the total spam score exceeds the spam score threshold. Note: • When making these modifications, you may want to re-adjust the spam score threshold. Please go back to the General tab in the Edit AntiSpam Setting window to adjust - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 94
Chapter 9: Security Settings 3. Tick the Auto learning checkbox to adjust the following settings: • Mark as spam if score is higher than: You will see the spam score threshold set up at the General tab. • Learn as spam if score is higher than: During spam detection, if the spam score is higher than - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 95
Chapter 9: Security Settings Note: • The reporting process involves collecting spam to a specific mailbox to undergo the learning process. Therefore, after enabling spam reporting, users can report spam and non-spam based on the following two methods: • If users receive messages using MailPlus, the - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 96
OK to complete the settings. DNSBL settings Postscreen allows the setup of multiple DNSBL servers. Matching criteria during the server check . 3. Click the Settings button to specify the DNSBL score threshold for rejecting services. 4. Click the Create button to add servers to be checked. Note: - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 97
Chapter 9: Security Settings 6. Click OK to complete the settings. Enable greylist When there is a new inbound message, the system will check if there are records of the same IP address, sender, or recipient as that of this inbound message. If no records are found, the message will be considered - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 98
Chapter 9: Security Settings 2. Click the Greylist Settings button to set up default actions for all sources or actions for a specific IP address or domain name. 3. In the Greylist Settings window, click the Settings button to set up the default action for all sources. 4. From the Action drop-down - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 99
Chapter 9: Security Settings 6. In the pop-up window, select a sender source and select an action from the Action dropdown menu. Note: • The domain source here is fetched from the IP address searched via DNS, not from MAIL FROM of a message. 7. Click OK to complete the settings. Antivirus Scan - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 100
ensure smooth running of security engines, we recommend using Synology NAS models with at least 2 GB RAM. Enable manually update virus definitions: • Auto-update virus definitions: Tick the checkbox to allow the system to download the latest virus definition files on a daily schedule. • Manual - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 101
if a message contains malicious links. • Use other third-party databases to download virus definitions: Uses Sanesecurity and other third-party databases to enhance virus detection. by McAfee and purchase the license using Synology Account. 2. Click Update Settings to view McAfee's information. 98 - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 102
issues or corrupted virus definition files, etc.), Antivirus by McAfee will not scan messages. Please resolve the problem or switch back to ClamAV. If a user manually disables Antivirus by McAfee, MailPlus Server will automatically switch to ClamAV. Chapter 9: Security Settings 3. Click Apply to - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 103
list If you have saved emails to the quarantine section, you can view and manage the quarantined emails. Please refer to the following instructions to adjust the settings of quarantine list: 1. Go to Security > Antivirus and click the Quarantine List button. 2. You can search for senders, recipients - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 104
Authentication The purpose of authentication is to verify a sender's identity to block fraudulent messages and protect against identity theft. • SPF (Sender Policy Framework): SPF mechanism verifies the legitimacy of a sender's host. SPF records for many domains are currently published in DNS and - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 105
Chapter 9: Security Settings 3. Click Apply to save the settings. DKIM You can enable DKIM verification to prevent messages from being modified and to protect against identity theft. Please refer to the following steps to adjust DKIM verification settings: 1. Go to Security > Authentication. 2. - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 106
Chapter 9: Security Settings 5. Click Apply to save the settings. Note: • Emails rejected by DKIM will be moved into the Spam mailbox in MailPlus 2.1 and above versions. A warning will appear when these emails are viewed on MailPlus clients. DMARC Since DMARC is based on SPF and DKIM verification, - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 107
Chapter 9: Security Settings MCP rules Set up MCP (Message Content Protection) rules and specify an MCP threshold score. When an email matches a rule's criteria, the rule score will be summed up to the total MCP score. If the total score exceeds the MCP threshold score, the system will filter out or - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 108
Criteria Contain Equal to Fit regular expression Description If the target section of an email contains the matching content, the email matches the rule. If the target section of an email is identical to the matching content, the email matches the rule. If the target section of an email contains - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 109
Chapter 9: Security Settings • Save to quarantine: Blocks email messages and saves them to the quarantine section. You can click the MCP Quarantine button to view the content of quarantine messages. Please refer to Quarantine list for more information on managing quarantined messages. • Deliver - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 110
2. Under the Content Scan section, tick the Enable dangerous content scan checkbox and adjust the following settings: • Reject partial messages: Rejects emails that are split across multiple incomplete messages (specifically email messages with Content-Type value of header message/ partial). • - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 111
Chapter 10: Monitor Settings Chapter 10: Monitor Settings Monitor Server Status You can quickly oversee the server operation status via a graphical interface: • Mail Traffic Monitor: Monitors the server's mail traffic by specific time intervals. • Threat Monitor: Shows the number of email threats - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 112
point on the Number of Mails chart represents the total number of emails (of a specific email traffic type) during the time interval. Please refer to the steps below to adjust the time interval: 1. Go to Server Management > Mail Monitor. 2. You can select date and time intervals from the Date field - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 113
page. • Antivirus function: See the antivirus engine status. To modify its relevant settings, click to jump to the page. • DNSBL Self-check: See if the Synology NAS is on a DNSBL blacklist. Click to see more details. 110 - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 114
Chapter 10: Monitor Settings View external threat analysis The external threat analysis displays sources of blocked inbound emails and the corresponding count statistics. 1. Go to Threat Monitor > Overview. 2. Under the External Threat Analysis section, you can find a threat map and count statistics - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 115
not enabled; however, the spam scanning will not be conducted. Check settings You can check if your MailPlus Server settings are the same as Synology's suggested settings in Check Settings. You can also see the effects of different settings here. Please refer to the following steps: 1. Go to Server - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 116
Chapter 10: Monitor Settings Monitor Mail Queue You can view pending emails in the mail queue and determine which action to take. Monitor messages in mail queue In the Queue page, you can check all emails that are pending to be sent to other servers or are to be resent to other servers after the - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 117
Chapter 10: Monitor Settings Manage messages in mail queue You can choose to immediately redeliver or cancel the delivery for messages in the queue. Please refer to the following steps to manage messages in the mail queue: 1. Go to Queue to do the following: • To redeliver a message, select the - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 118
10: Monitor Settings Monitor Mail Log Mail logs record all activities of the server. You can view log content to find the root problems and the solutions to problems. Please note that log files may account for a large capacity of storage space. The following log settings can be configured in the - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 119
Chapter 10: Monitor Settings View security logs Security logs display the time and date an event is generated, along with the source, sender, recipient, title, type, and event description. Security logs are categorized as follows: Rejected, Spam, Virus, DNSBL, Malicious Content, Attachment Filter, - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 120
Settings View external database If you have archived logs, generated a log database, or downloaded log files, you can view log content stored in External database. Please refer to External database. 3. Find the location of your external database on the Synology NAS. 4. Click the Select button. 117 - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 121
Chapter 10: Monitor Settings Search logs At Auditing > Log, you can search for logs using the simple search or the advanced search. • Simple search: You can enter keywords in the search field in the upper-right corner of the page: • For Mail log, the entered keywords are used to search for content - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 122
• Advanced search: You can click the magnifying glass icon in the search bar in the upperright corner of the page. Set up search criteria for each item to conduct a precise advanced search. Click OK after you finish the settings. From the Status drop-down menu, you can select Within domain to search - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 123
Chapter 10: Monitor Settings Archive logs You can configure log archiving settings. MailPlus Server will archive mail logs, security logs, and Postfix logs on a user-defined schedule. Please note that the archive feature will be automatically disabled once you cannot access the shared folder. Please - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 124
Transfer Postfix logs to other syslog servers Please refer to the following steps to send Postfix logs to other syslog servers: 1. Go to Auditing > Log Management. 2. Under the Log Transfer section, tick the Transfer logs to a syslog server checkbox. 3. Enter the information of the syslog server. 4. - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 125
You can save or remove mail logs, security logs, admin logs, or Postfix logs at Auditing > Log List. Please refer to the following steps to download and delete log files: 1. Go to Auditing > Log List. 2. Select Mail Log, Security Log, Admin Log, or Postfix Logs from the drop-down menu at - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 126
Generate log database If you have enabled Transfer logs to the secondary server, you can convert received log content back to database files using the Generate log database feature. You can View external database at Auditing > Log to view files in the log database. 1. Go to Auditing > Log List. 2. - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 127
Chapter 10: Monitor Settings Set up daily reports You can enable the daily report feature to allow Postfix logs from the previous day to be sent to a specific email address. Please refer to the following steps to set up daily reports. 1. Go to Auditing > Report. 2. Tick the Enable daily report - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 128
keywords. For example, to look for an email about GDPR sent after May 25th, 2018 from the address [email protected], you can enter after:2018/05/25 AND from:[email protected] AND GDPR as your search condition. Search Operator Usage Example from: Messages from the specified sender from:amy - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 129
10: Monitor Settings View mail search results 1. Go to Auditing > Mail Search and select a complete search task. 2. On the right panel, you can Download task reports or click View Result for further details and actions. Task reports allow you to view the details of a task, including the number of - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 130
original emails or only the mail list. 5. The exported mail list can be found as a file named export_list.csv and can be edited with editors supporting .csv files. If you wish to distribute an auditing task, you can split the record into multiple files. Exported original mails can be found as - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 131
two solutions: single node configuration and high-availability configuration. Single node configuration requires one Synology NAS to run mail services while high-availability configuration requires two Synology NAS to form a high-availability (HA) cluster, which can ensure uninterrupted mail - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 132
systems and cannot run on the same Synology NAS simultaneously. • MailPlus HA and SHA are unavailable on VDSM. For more details, please refer to VDSM Admin Guide. • Synology High Availability is supported for MailPlus 2.2 and above. • If service continuity is required, please consider MailPlus high - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 133
during the HA cluster creation. • It is recommended that both DSM volumes are the same size and have sufficient space because all emails should be set up to perform manual network configuration. 3. Both Synology NAS must join the same domain: • Both Synology NAS must join a Windows Active Directory - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 134
set up a domain or an LDAP server for account management. Please note that using self-hosted LDAP or domain services has the risk of mail service interruption when the Synology NAS hosting the directory is abnormal or unresponsive. 4. Prepare an internal IP address and external IP address for the HA - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 135
Recovery 5. Enter the IP address of the secondary server in the Server Address field or select a Synology NAS to use as the secondary server from the Server Address drop-down menu. Synology NAS under the same LAN will be searched and included in this drop-down menu. Note: • Secondary servers - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 136
: • During the first synchronization, MailPlus services are available but relatively slow due to and speed up the synchronization. For detailed instructions on using Hyper Backup to back up the Primary Server Settings section, you can select a Synology NAS to act as the primary server of the HA - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 137
data will be synchronized across the two Synology NAS to ensure data consistency. After the no longer be used by any of the Synology NAS. You may need to adjust the port forwarding to remove one of the Synology NAS from the HA cluster: 1. Sign in to DSM of the Synology NAS you wish to keep - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 138
DMZ) settings of your firewall device or modify your DNS records. Server malfunction When one of the Synology NAS in the HA cluster malfunctions, the other one will continue to provide mail services. The primary and secondary servers mentioned in the following sections refer to the original roles of - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 139
secondary server malfunctions, the original primary server will take over the internal IP address of the HA cluster and process all service requests independently. Please recover the original secondary server at the earliest opportunity. If the original secondary server cannot be recovered, please - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 140
Back up and Restore Email You can use backup features on DSM to back up MailPlus Server. MailPlus Server backup includes the up mail system configuration to a MailPlus compatible Synology NAS using Hyper Backup. 1. Launch Hyper Backup on the source Synology NAS. 2. Click the plus icon (+) in - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 141
and email messages to a MailPlus compatible Synology NAS through sync tasks: Enable shared folder sync You need to enable Shared Folder Sync on the destination Synology NAS. 1. Sign in to DSM. 2. Go to Control Panel > File Services > rsync. 3. Tick the Enable rsync service checkbox to enable Shared - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 142
once any changes occur to the source shared folder. • Run sync manually: Syncs from the source shared folder only when you click the button. according to the specified schedule. Manage sync tasks Sign in to the source Synology NAS and refer to the following steps to manage sync tasks: 1. Go to - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 143
• Please do not use Synology Drive, Cloud Station Server, data from MailPlus_1, please manually move data to the destination Synology NAS. Please Synology NAS that's going to be restored: • Stop the Synology MailPlus Server and Synology compatible with MailPlus Server 1.0-164 (and above) running on - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 144
service for viewing, managing, and sending emails. For detailed information on the MailPlus setup, please refer to the Set up MailPlus Client section. This chapter will guide you through MailPlus configuration and interface navigation. For detailed instructions the Draft box to resume writing. 141 - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 145
Chapter 12: MailPlus Navigation • Reply to an email: There are three ways to reply to an email in MailPlus: • Reply: Click Reply to reply to the sender. • Reply all: Click Reply all to reply to all recipients (including CC recipients) at once. • Forward: Click Forward if you want to send an email to - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 146
Synology MailPlus Server. Contacts and its related settings can be found in the App Launcher. In this chapter, we will guide you through the configuration of SMTP, OpenPGP, and Blacklist/ Whitelist. If you need detailed instructions articles or tutorials of your mail service provider. • SMTP port: - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 147
Chapter 12: MailPlus Navigation • Authentication required: Tick the checkbox if your SMTP server requires authentication. • Username: Enter your email address. • Password: Enter your email password. • Secure connection (TLS) required: Tick the checkbox to secure connections with TLS certificates. • - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 148
• When composing an email, you can switch between SMTP servers in the From: field. Chapter 12: MailPlus Navigation Encrypt emails via OpenPGP OpenPGP (Pretty Good Privacy) is a key-based encryption technology used for email encryption. OpenPGP encrypts emails so that only intended recipients can - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 149
Chapter 12: MailPlus Navigation Manage OpenPGP keys • Public key: Click the Export button to export the public key and give it to senders who should encrypt emails for you. • Private key: Keep the private key to yourself because it is used to decrypt emails sent to you. • If you need to send others - Synology RS4021xs | Synology MailPlus Server Administrator s Guide - Based on Ma - Page 150
specifications and product descriptions at any time, without notice. Copyright © 2020 Synology Inc. All rights reserved. ® Synology and other names of Synology Products are proprietary marks or registered trademarks of Synology Inc. Other products and company names mentioned herein are trademarks of
Administrator's Guide for
Synology MailPlus Server
Based on
Synology MailPlus Server 2.3