Part of the marketing effort involves sending out periodic newsletter mailings to people who've expressed interest. We're coming up on the 4th year of the conference, so that list is in the low thousands. But, we discovered that a rather large chunk of the list--the people with AOL accounts--weren't receiving the newsletter. On investigation, it seemed that we (or Jerry, since he was sending the newsletters) had run afoul of AOL's rather obscure spam filtering, and that AOL was quietly dropping email on the groud.
Enter Perl (again). After reading up on what I could find about AOL's filtering scheme (a lot to read, since a lot of people have run into it), I put together a forwarder that would send out a mailing in small batches, a few an hour. (Easy stuff, using MIME::Lite.) That seems to be enough to come in under AOL's radar, though it takes 44 hours to get through the list.
Has anyone else come up with a clever solution to getting a mailing through to people who've opted-in, but whose providers have implemented SPAM filters? Advice seems to be all over the map. We had to work around bounces from another provider when one newsletter used "extreme" several times (when mentioning eXtreme Programming).