"These applications appear to adopt the "fire-and-forget" methodology. That is, they attempt to send the spam to one or several MX hosts for a domain, but then never attempt a true retry as a real MTA would."
I strongly disagree. A vaste majority of spammers actually use real mail servers like Qmail. Or strange spam-specific software with support for retries.
Apart from Spam Assassin, I'm using OpenBSD built-in "spamd" ip-based filter. A quick look at the spamd log files shows that the same spammers retry over and over, usually during 7 days.
What I like in Greylistings is that it actually prioritizes mails. A mail coming from a known source will be processed before a mail coming from an unknown source (that will have to wait for the next try) . Not really an antispam feature, but still nice to have.
I'm skeptical (Score:2)
"These applications appear to adopt the "fire-and-forget" methodology. That is, they attempt to send the spam to one or several MX hosts for a domain, but then never attempt a true retry as a real MTA would."
I strongly disagree. A vaste majority of spammers actually use real mail servers like Qmail. Or strange spam-specific software with support for retries.
Apart from Spam Assassin, I'm using OpenBSD built-in "spamd" ip-based filter. A quick look at the spamd log files shows that the same spammers retry over and over, usually during 7 days.
What I like in Greylistings is that it actually prioritizes mails. A mail coming from a known source will be processed before a mail coming from an unknown source (that will have to wait for the next try) . Not really an antispam feature, but still nice to have.