[Dovecot] Cannot authenticate with new Red Hat/Fedora SHA512

[Timo Sirainen]

On Tue, 2011-02-01 at 16:01 +0000, John Cooper wrote:
> >> cat /etc/shadow
> >> user1:$6$<salt>$<password>:15006:0:99999:7:::
..
> passdb {
>    driver = pam
> }

PAM reads the shadow file and does the authentication, not Dovecot. So
it has nothing to do with passwords being SHA512. More likely it's the
same generic PAM authentication problem explained in
http://wiki2.dovecot.org/WhyDoesItNotWork