Re: [Dovecot] dovecot: lda(root): Fatal: Invalid user settings. Refer to server log for more information.

On Fri, Nov 16, 2012 at 10:15:24PM +0000, Ben Morrow wrote:

postfix's local(8) will not allow you to deliver mail as root.

Strictly speaking it will deliver to/as root, but not if invoking commands, which is what the OP was doing.

http://rob0.nodns4.us/ -- system administration and consulting Offlist GMX mail is seen only if "/dev/rob0" is in the Subject: