Well, I think you're going to have to narrow it down to which headers are
actually causing it, if that's actually the case.
Almost all ESPs add a list-unsub header. We know that alone doesn't cause
Gmail blocking.
I also add X-Auto-Response-Suppress and auto-submitted headers to some
automated rep
Hi all,
In the process of changing ESPs, we have turned off some ancillary headers
until the new backend code supported them.
The headers we used (among others) included: list-id (requested by yandex.ru
postoffice console, auto-submitted (suggested on this list to quiesce
automatic responses), X-P
