Switching to dovecot LMTP appears to have change the information in the received header, which appears to be causing my spam filter to wig out and mark local to local emails as spam.
Here’s what the received header used to look like:
Received: from [10.0.5.3] (c-71-229-144-93.hsd1.co.comcast.net [71.229.144.93]) by mail.covisp.net (Postfix) with ESMTPS id B67B8118AD59 for kreme@kreme.com; Sun, 16 Aug 2009 22:19:02 -0600 (MDT)
As opposed to now:
Received: from darth.lan (c-73-14.161.160.hsd1.co.comcast.net [73.14.161.160]) by mail.covisp.net(Postfix 3.4.5/8.13.0) with SMTP id unknown; Sun, 16 Jun 2019 15:26:32 -0600 (envelope-from kreme@kreme.com)
The first has an ESMTPS id and the other has SMTP id unknown, which seems to be causing Spamass-milter to treat the LMTP emails as unauthenticated and then ding them for being from public IPs.
-- Thanks to the human heart by which we live, Thanks to its tenderness, its joys, and fears, To me the meanest flower that blows can give Thoughts that do often lie too deep for tears