[Top] [All Lists]

Re: [ietf-smtp] test for port 25 of sending MTA - for spam detection

2013-08-23 06:41:50
On Fri, 23 Aug 2013, keld wrote:
Thi idea was to use it as a check in addition to DNSBL etc.

The advantage over DNSBL is that for DNSBL you first need to register the offending site with DNSBL.

Not necessarily. See for instance

FWIW, I just checked the sending IP addresses a bunch of spam emails that weren't listed at Spamhaus ZEN at time of delivery. A significant minority of them (~ 40%) was listening on port 25.

At the same time, several IP addresses that were sending legitimate email weren't.

Perhaps, if you do it very carefully, adding a tiny score for emails delivered from an IP address that wasn't listening on port 25 will improve your filter's performance by 0.03%.

Or perhaps it won't.

ietf-smtp mailing list