Hello folks, over the last couple of months I have received some nasty spam, delivered by the Yahoo mail servers.
After looking at the headers it became clear what the issue was: It seems that Yahoo (at least yahoo.co.jp) is allowing emails from @gmail.com senders to be sent through their servers. The funny thing is, that there is a @gmail.com address in both the 'From:' and 'Return-Path:' headers, but a @yahoo.com address in the 'Reply-To:' and 'Sender:' headers. Somehow Yahoo sees no problem in that and is happy to DKIM sign those emails with a correct *Yahoo* signature. Over on my side, the receiving end of these emails, there is my spamassassin. SA discovers the DKIM signature and is able to validate this signature against the Yahoo server which is totally undesirable in my opinion. Maybe strict DKIM alignment is not always the best choice, because sometimes the emails are signed by different servers without sharing one signing key for the entire domain. So is there any way to make SA perform at least a relaxed DKIM alignment check on the headers so that the DKIM signature domain has to belong to the 'From:' address? Any hints or suggestions are much appreciated. Cheers, Thore --
signature.asc
Description: PGP signature
