> > If you are using sendmail as the MTA, Dovecot is not involved for > authentication on mail submission. The maillog line you provided does not > contain enough information to tell what triggered the error.
Not totally true. Typical cyrus sasl2 implementation used with sendmail uses an imap server for smtp authentication. I recall having to tweak the sasl2 configuration on my own sendmail server to talk correctly with dovecot. I don't recall the exact tweaks. I suggest reviewing the sasl2 implementation's documentation (the OP has not to my knowledge stated which sasl implementation he is using). It sounds like an sasl2 problem, not necessarily a dovecot problem.
