Hi,
Monitoring the mail system, I've found that Google still has us rate limited. Trying to understand why, I've come up with the following reason:
Google verifies DKIM as part of their criteria for identifying SPAM. We sign our outgoing mail, so, there shouldn't be a problem. However, some mail *already* has a DKIM signature. Still no problem, but most mailing lists change the Subject: line by prepending the mailing list name.
Now *that*'s a problem: it invalidates the pre-existing signature! So, simply strip the old DKIM headers, you might say. That will make the problem go away. Well, in fact it probably doesn't: domains which use DKIM can also state a policy that all mail from the domain should be signed. Stripping the DKIM signature makes the mail invalid with respect to that policy, again triggering the SPAM rules.
My conclusion: we have to stop munging the Subject: line in the mailman mailing lists.
Any comments?