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I have been googling for a couple hours trying to figure this out. This is happening as we speak on a LIVE mail server, which I thought I had tested properly before rolling LIVE.

What we have is a Postfix server setup with IMAP/POP3, etc. 95% of my users just get delivered locally to postfix. But what I have is 5 users, that need to be forwarded to an exchange server.

The domain is the same for all the users so I can't split by domain.

Noone can send email to these users that are on the exchange system? I keep getting "User unknown in virtual alias table" error messages.

I set up transport maps for the users with smtp: but I can't get the mail to deliver?

Is there some setting somewhere where I can configure that there are extra email addresses that should still be accepted??

Here's my

debug_peer_level = 9
debugger_command =
 xxgdb $daemon_directory/$process_name $process_id & sleep 5
sendmail_path = /usr/sbin/sendmail.postfix
newaliases_path = /usr/bin/newaliases.postfix
mailq_path = /usr/bin/mailq.postfix
setgid_group = postdrop
html_directory = no
manpage_directory = /usr/share/man
sample_directory = /usr/share/doc/postfix-2.3.3/samples
readme_directory = /usr/share/doc/postfix-2.3.3/README_FILES
virtual_alias_maps = hash:/etc/postfix/virtual
sender_bcc_maps = hash:/etc/postfix/bcc
mailbox_command = /usr/bin/procmail-wrapper -o -a $DOMAIN -d $LOGNAME
home_mailbox = Maildir/
smtpd_sasl_auth_enable = yes
broken_sasl_auth_clients = yes
smtpd_recipient_restrictions = permit_mynetworks permit_sasl_authenticated reject_unauth_destination
myhostname = <hostname>
mydomain = <domain>
smtpd_banner = Hello.  This server uses anti-spam and anti-virus functions.
relayhost = <relayserver>:<port>
transport_maps = hash:/etc/postfix/transport
#fallback_transport = smtp:<ip>:<port>
#fallback_transport_maps = hash:/etc/postfix/fallback_map
luser_relay = dcmoody@<domain>

I've tried adding the email addresses to the virtual file pointing to themselves and that didn't work.

Please help!

share|improve this question
Did you remember to postmap /etc/postfix/transport? – 84104 Dec 15 '11 at 18:01
up vote 1 down vote accepted

In Exchange, add a different namespace for email (like testdomain.local or somesuch), assign email addresses with that address to the users who need forwarding. Set up forwarding in Postfix to forward to usera@testdomain.local (or .com or whatever - I don't know Postfix well enough to know if it'll accept non-publicly routable TLDs like Exchange will). That'll fix the issue for the most part, though you'll need to make sure Exchange knows it's non-authoritative for the domain.

share|improve this answer
Thank you for this solution. I actually just tried something like this out on my own and that is what worked. – dcmoody Dec 15 '11 at 18:23

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