If you happened to find or block on pam auth in 2.3.1 here a few Details. I ran into the same when testing.
Exhaustive debugging led me to enough data to find [1] and from there [2][3]. With this applied until upstream settles how they want to resolve it eventually things work much better for me. Hope that helps on your >=2.3.1 efforts. [1]: https://bugzilla.redhat.com/show_bug.cgi?id=1564348 [2]: https://github.com/dovecot/core/pull/71 [3]: https://github.com/dovecot/core/pull/71/commits/3a3d9c77c243bc1097039cb70a0029e0c108efbb -- Christian Ehrhardt Software Engineer, Ubuntu Server Canonical Ltd
