s/qmail/DOCについて、ここに記述してください。
Contents
7. Malware Protection
http://fehcom.de/sqmail/sqmaildoc_07.html
7.5 Spam Prevention
Once, a handle regarding sending from bot-nets is given, control can be re-established. Two means are used for this purpose:
Greylisting: The sender is initially greylisted and a sending attempt is accepted only after n>seconds. This requires to set up a state-table per connection attempt.
- Greetdelay: The sender is 'halted' for n seconds before sending the required 'Helo' greeting from the server. This feature discourages any illegitimate sender since it sucks up resources to send the mail.
Both methods work equally well; but both have their pros and cons. Using rblsmtpd Greetdelay is supported and works incredible well; without the need to maintain a state table for SMTP connections.