Spam Prevention Tools
Current estimates put the proliferation of spam at over 90% of all email. To say that this is a problem is an understatement. Luckily, developers have created numerous tools to aid in the identification of spam.
Techniques
- Delay Tactics (Greylisting, GreetDelay)
- Spam Identification (SpamAssassin, DSpam)
- Spam Rejection (RBL, SURBL)
- Challenge/Response (TMDA, ASK)
- Other (Other software that does not fit in the above categories)
Popular Open Source Solutions
- Spamassassin
- One of the most well known open-source spam identification tools. Spamassassin uses a series of rules written to identify spam, as well as a Bayesian filtering system that learns from known spam and ham.
- DSpam
- DSpam takes another approach to spam identification. Dspam relies completely on algorithm based identification. It is not quite as well known as Spamassassin, but has a similar track record for identification of spam.
- spamdyke
- spamdyke focuses on rejecting spam before qmail accepts it. It has filters for missing/suspicious reverse DNS names, DNS RBLs, greeting delays, blacklists (and whitelists), graylisting, limiting the number of recipients per message, connection timeouts and more. It provides much better logging than qmail does by default. It supports SMTP AUTH and will even provide SMTP AUTH for unpatched qmail servers! Installing spamdyke does not require patching or recompiling qmail.