[Dovecot] Hybrid of linux user accounts and virtual user accounts configuration

[Derek Winterstien]

Hello again.  I have my virtual users working now.  Postfix delivers 
mail, and dovecot retrieves it for pop and imap users in the virtual 
user database.  Just one more thing though, it is understood that 
dovecot is going to ask pam to check first for a unix account, which 
will fail, then dovecot tries the virtual user text file, and 
succeeds when the user is located.  However, the pam error generated 
in the secure log is ugly.

auth: pam_succeed_if(dovecot:auth): error retrieving information about user foo

I would like to suppress this error, only when dovecot succeeds from 
the virtual user text file.  However, still report the pam error when 
no valid user exists in either.  Is this possible?