Apparently, GMail has been filing invalid spam complaints with DFN (the germany-wide university and research network backbone).

This is the second time we were forwarded this complaint all the way down to us. I know exactly which mail it is. The IP is the firewalls “private” IP, so no other service is on that IP (it’s not the masquerading IP). The time matches exactly the time of an email delivered to GMail.

Therefore I’m 100% sure which mail they are considering to be spam. However, it is not. It’s not in the “spam” folder in GMail either. No SPF violation. Valid reverse lookup in the appropriate domain. Single-hop SMTP delivery. Firewall to gmail mailserver.

It’s our daily snort report, that is considered spam every few weeks.

That totally sucks, that a perfectly valid and correctly sent email, that is also delivered correctly, is reported as spam amongst the big ISPs. Unfortunately I don’t have any details on who is filing the complaint, but it certainly is somewhere among the big ISPs. And traceroute shows a direct peering of Google with the DFN at DeCIX.

[Update: 2006-06-19 04:25:05 http://cbl.abuseat.org thats all I know of the “complaint” – but I have no idea how abuseat.org is involved in this. But this again is the valid daily snort email, so I wish they’d just stop reporting this false-positive over and over again…]