Re: Mail server is to strict with filtering? And virus mails get through sometimes! -
21-04-2004
The spammers have developed a new technique which almost always bypasses most spam filters:
All spam filters which are based on some kind of statistical analysis (e.g. bayes or razor) depend on statistical analyzable data. They assume that most spam has common attributes e.g. words like "viagra" or whatever the spam wants to advertise. And they assume some other criterias like a minimum percentage of HTML code.
What the spammers do to bypass the filters is very simple but effective:
- avoid those keywords
- use 1337 language for keywords !!!!
- add some random text to the mail to make each mail unique
@spamassassin:
Don't use Subject: rewriting, instead use the X-Spam headers. Your Subject: lines won't get altered and almost every mail client can filter for custom header lines.
@general suggestion:
Use IMAP instead of POP3.
With IMAP you can have your mail folders at the server and also filter the mails at the server into different folders. Users with slow connections benefit from another feature too: the e-mail clients doesn't need to download the entire messages, instead he only downloads some parts of the header to get an overview of the mails. And only if the user opens a message it's downloaded. And even then attachements are only downloaded at request.
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