7.3. Basic Evasion: Tips on How to Beat a Filter

Spam filter evasion can be summed up in one sentence: from the subject line to the reply address, every element of spam must look like the dayto- day e-mails people receive. Spam cannot contain any suspicious content because spam detection is highly intelligent and spam filters can catch and remove large quantities of messages that spammers send. As can be seen from the different types of spam filters available, many different and unique techniques are used to identify a message's validity and the legitimacy of their contents. This section focuses on defeating ruleand hash-based filters.

Defeating a spam filter can be hard, but it often just comes back to the golden rule of spam: numbers. If you send ten million spam e-mails and only six million messages are read, you can say that you expect an instant 40 percent loss with any mailings you send out. If you send twice as much e-mail as usual, in theory you come closer to breaking even. Flooding the world with spam can dilute the impact of your product, but if enough spam is sent, rewards will eventually be gained.