thanks for your input. i wanted to check one thing.
> That said, my email server (not lists.sr.ht) seems to re-format the header> after verifying the signature and chokes on your DKIM-Signature header. It> re-formats `d=\r\nmessagingengine.com` with `d= messagingengine.com` for> instance. I don't know if some email servers could be confused by that and> fail to verify signatures which have parameters split over two lines after> the equal sign.
when you said 'd=\r\nmessagingengine.com', i'm assuming there was some
whitespace (maybe the canonical four spaces?) between the '\r\n' and the
'messagingengine.com'. is that true?
ps -- pair.com -- my isp -- support got back to me, and seem to be
giving the problem having reasonable attention, so maybe they will
figure out the combination of software they are using plus input that
generates the problem.