IT geek 31 <itgeek31@googlemail.com> writes:

I've recently switched to LMTP as I'm now using mdbox. However since switching, mails sent to the root account do not get delivered due to the following error:

May 1 18:20:17 Server1 postfix/lmtp[13019]: CAEE91F851: to=<root@test.com>, relay=mail.test.com[private/dovecot-lmtp], delay=1097, delays=1096/0.45/0.43/0.46, dsn=4.3.0, status=deferred (host mail.test.com[private/dovecot-lmtp] said: 451 4.3.0 <root@test.com> Invalid user settings. Refer to server log for more information. (in reply to RCPT TO command))

This setting:

first_valid_uid = 1010

will need to be changed to "0", or better yet, as others have suggested, alias root to some user with UID within 1010..1020.

The dovecot logs that you ought to see will be something like

May  1 16:12:11 viol dovecot: lda: Error: user root: Mail access
	for users with UID 0 not permitted (see first_valid_uid
	in config file, uid from userdb lookup).

Joseph Tam <jtam.home@gmail.com>