I have dovecot working with PAM and Samba DC authentication for IMAP. However when I'm attempting to pass emails from postfix via LMTP I don't actually need to authenticate LMTP I'm happy to check for valid users upstream.

I'm getting the error: Feb 06 15:11:39 Debian-server postfix/local[178200]: ADF0E78713C: passing dom.username@Debian-server.sr.local to transport=lmtp Feb 06 15:11:39 Debian-server dovecot[178075]: auth: Error: static(dom.username): passdb doesn't support lookups, can't verify user's existence Feb 06 15:11:39 Debian-server dovecot[178075]: lmtp(dom.username@Debian-server.sr.local)<178233>: Error: auth-master: userdb lookup(dom.username@Debian-server.sr.local): Auth USER lookup failed Feb 06 15:11:39 Debian-server dovecot[178075]: lmtp(178233): Error: lmtp-server: conn unix:pid=178201,uid=111 [4]: rcpt dom.username@Debian-server.sr.local: Failed to lookup user dom.usernamey@Debian-server.sr.local: Internal error occurred. Refer to server log for more information.

Doveconf -n: auth_username_format = %Ln disable_plaintext_auth = no mail_gid = vmail mail_location = maildir:/var/mail/virtual/%d/%n mail_privileged_group = mail mail_uid = vmail namespace inbox { inbox = yes location = mailbox Drafts { special_use = \Drafts } mailbox Junk { special_use = \Junk } mailbox Sent { special_use = \Sent } mailbox "Sent Messages" { special_use = \Sent } mailbox Trash { special_use = \Trash } prefix = } passdb { args = mail driver = pam } plugin { sieve = file:~/sieve;active=~/.dovecot.sieve } protocols = " imap lmtp lmtp" service auth { unix_listener /var/spool/postfix/private/auth { group = postfix mode = 0666 user = postfix } } service lmtp { unix_listener /var/spool/postfix/private/dovecot-lmtp { group = postfix mode = 0600 user = postfix } } ssl_cert =