IBM AH0QXML User Guide - Page 22

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Lotus Domino 6 spam Survival Guide for IBM eServer

2.1.3

Confusing the harvesters

The e-mail harvesters are programs that gather e-mail addresses of a specific

format. If the format of the address does not meet the criteria of the program it

will not be gathered for spam usage.

Mailto tags

One area where you may want to employ this tactic is on your public Internet site.

Harvesters are notorious for going after any address in a mailto: tag. One way to

protect your addresses on the Web site is to write the mailto: tag with a

hexadecimal e-mail address rather than an ASCII address. All browsers can

understand these addresses while harvesting programs will not pick them up.

Here is an example of an address converted to hexadecimal:

ASCII: <a href=mailto:me%40mydomain.dom>[email protected]</a>

Hex:

<a href= mailto:%6d%65%40%6d%79%64%6f%6d%61%69%6e%2e%64%6f%6d> Email

me</a>

Here is an example of a perl script that will convert ASCII addresses to hex:

#! /usr/bin/perl

# Little perl program to convert ascii email addresses to hex

# to avoid spam harvesting from mailto: tags

my $addr = shift

or die "usage: $0 email\@address.dom\n";

$addr =~ s/(.)/ sprintf('%%%2x',ord($1)) /ge;

chomp($addr);

print "$addr\n";

Address obfuscation

If you are posting to a newsgroup or to a Web discussion board where you

suspect that your address may be gathered, consider

munging

. Address

munging involves changing your real e-mail address in a way that will make it

unavailable for harvesting. Normally this involves adding a

"NOSPAM"

or some

other text string that other people will know to remove before sending mail to that

address. Harvesting programs are often not smart enough to distinguish between

a munged address and a real address. An example of such an e-mail address is

[email protected].

2.1.4

Inform Users

The more users know about the cause of their addresses being picked up by

spammers, the greater the chance that they can avoid getting on the list.

Section	Page
Front cover	1
Contents	5
Notices	7
Trademarks	8
Preface	9
The team that wrote this redbook	9
Become a published author	11
Comments welcome	12
Chapter 1. Introduction	13
1.1 Definition of spam	14
1.2 Categorizing spam	14
Chapter 2. Preventing unwanted e-mail and spam	19
2.1 Spam avoidance techniques	20
2.1.1 Passive harvesting attacks	20
2.1.2 Avoiding harvesting	21
2.1.3 Confusing the harvesters	22
2.1.4 Inform Users	22
2.2 How to block spam	24
2.2.1 At the gateway	25
2.2.2 At the server	25
2.2.3 By the end user	26
2.2.4 Selecting the best approach	26
2.2.5 Managing the ongoing anti-spam campaign	27
2.2.6 Summary	28
Chapter 3. Domino 6 anti-spam architecture	29
3.1 The Domino messaging environment	30
3.2 Domino 6 messaging components	32
3.2.1 SMTP Listener/Server	33
3.2.2 Router	35
3.3 Domino 6 anti-spam configuration	35
3.3.1 Server configuration features	36
3.3.2 User configuration features	37
3.4 Common problems and solutions	37
Chapter 4. Domino 6 Server anti-spam features	41
4.1 How to detect spam	42
4.1.1 Examining the message properties	42
4.1.2 Separating legitimate e-mail from spam based on content	43
4.2 Controlling connections from spammers	44
4.2.1 DNS Blacklist filters	44
4.2.2 Inbound Intended Recipients Controls	48
4.2.3 Disable routing mail to groups	51
4.2.4 Inbound connection controls	53
4.2.5 Inbound sender controls	54
4.3 Controlling delivery of spam	57
4.3.1 Server mail rules	57
4.4 Controlling use of your server as a relay	66
4.4.1 Inbound relay controls	66
4.4.2 Inbound relay enforcement	71
4.5 Protecting your Domino server from active address harvesting attacks	74
4.5.1 SMTP harvesting attacks	74
4.5.2 Spam mail bombing	74
4.5.3 Direct SMTP RCPT TO harvesting	74
4.5.4 Defending against active attacks	75
Chapter 5. Using mail file rules to prevent spam	77
5.1 Distinguishing between spam and legitimate e-mail	78
5.2 Mail file rules	80
5.2.1 Setting up mail file rules	80
5.2.2 Developing anti-spam mail file rules	83
5.2.3 Viewing mail rules and the evaluation sequence	89
5.2.4 Monitoring mail file rules	90
Chapter 6. Third party anti-spam products	93
6.1 Anti-spam products for Notes and Domino	94
6.1.1 spamJam for Lotus Notes and Domino	94
6.1.2 SpamEraser for Lotus Notes and Domino 6	97
6.1.3 iQ.Suite	100
6.1.4 ScanMail for Lotus Notes with eManager	101
6.1.5 XM SpamStop	104
6.1.6 Other anti-spam products for Notes and Domino	106
6.2 Anti-spam server and gateway products and services	106
6.2.1 BrightMail Anti-Spam 4.0 from BrightMail, Inc.	106
6.2.2 ActiveState PureMessage	107
6.2.3 Trend Micro Inc. products	109
6.2.4 Other anti-spam server or gateway products and services	110
Related publications	111
IBM Redbooks	111
Referenced Web sites	111
How to get IBM Redbooks	112
IBM Redbooks collections	112
Index	113

IBM AH0QXML User Guide - Page 22

Confusing the harvesters, 2.1.4 Inform Users, Mailto tags, Address obfuscation

Page 22 highlights