mail forwarding - User unknown in virtual alias table

I have a mail account set up that receives email fine.

Wanting copies of all emails to go to an off server account, I have set up mail forwarding. The email is still received, but I get an error returned to the sender:

This is the mail system at host alpha.???.com.

I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to

If you do so, please include this problem report. You can delete your own text from the attached returned message.

              The mail system

info@xxx.co.uk (expanded from info@yyy.co.uk): User unknown in virtual alias table

Final-Recipient: rfc822; info@xxx.co.uk Original-Recipient: rfc822;info@yyy.co.uk Action: failed Status: 5.0.0 Diagnostic-Code: X-Postfix; User unknown in virtual alias table

The mail log reads:

Jun 21 23:12:16 alpha postfix/smtpd[2918]: connect from mail-fx0-f223.google.com[209.85.220.223] Jun 21 23:12:16 alpha postfix/smtpd[2918]: 11F0210337: client=mail-fx0-f223.google.com[209.85.220.223] Jun 21 23:12:16 alpha postfix/cleanup[2922]: 11F0210337: message-id=b7b3b7e10906211512r37060129w574d8f5ee9e1f848@mail.gmail.com Jun 21 23:12:16 alpha postfix/qmgr[1156]: 11F0210337: from=mr@googlemail.com, size=5417, nrcpt=1 (queue active) Jun 21 23:12:22 alpha postfix/local[2923]: 11F0210337: to=<info.yyy.co.uk@alpha.???.com>, orig_to=info@yyy.co.uk, relay=local, delay=6.2, delays=0.09/0.01/0/6.1, dsn=2.0.0, status=sent (delivered to command: /usr/bin/procmail-wrapper -o -a $DOMAIN -d $LOGNAME) Jun 21 23:12:22 alpha postfix/cleanup[2922]: 23324103D0: message-id=b7b3b7e10906211512r37060129w574d8f5ee9e1f848@mail.gmail.com Jun 21 23:12:22 alpha postfix/local[2923]: 11F0210337: to=<info.yyyy.co.uk@alpha.???.com>, orig_to=info@yyy.co.uk, relay=local, delay=6.2, delays=0.09/0.01/0/6.1, dsn=2.0.0, status=sent (forwarded as 23324103D0) Jun 21 23:12:22 alpha postfix/qmgr[1156]: 23324103D0: from=mr@googlemail.com, size=5596, nrcpt=1 (queue active) Jun 21 23:12:22 alpha postfix/qmgr[1156]: 11F0210337: removed Jun 21 23:12:22 alpha postfix/error[2935]: 23324103D0: to=mr@xxx.co.uk, orig_to=info@yyy.co.uk, relay=none, delay=6.1, delays=6.1/0.01/0/0.01, dsn=5.0.0, status=bounced (User unknown in virtual alias table) Jun 21 23:12:22 alpha postfix/cleanup[2922]: 44D0B103D1: message-id=<20090621221222.44D0B103D1@alpha.???.com> Jun 21 23:12:22 alpha postfix/qmgr[1156]: 44D0B103D1: from=<>, size=7549, nrcpt=1 (queue active) Jun 21 23:12:22 alpha postfix/bounce[2936]: 23324103D0: sender non-delivery notification: 44D0B103D1 Jun 21 23:12:22 alpha postfix/qmgr[1156]: 23324103D0: removed Jun 21 23:12:23 alpha postfix/smtp[2937]: 44D0B103D1: to=mr@googlemail.com, relay=gmail-smtp-in.l.google.com[209.85.219.3]:25, delay=0.76, delays=0.01/0.01/0.28/0.46, dsn=2.0.0, status=sent (250 2.0.0 OK 1245622343 3si11156965ewy.39) Jun 21 23:12:23 alpha postfix/qmgr[1156]: 44D0B103D1: removed Jun 21 23:12:46 alpha postfix/smtpd[2918]: disconnect from mail-fx0-f223.google.com[209.85.220.223]

??? is the vm server yyy is the vm domain xxx id the email forwarding domain.

I have had a search around the forums and can see this being reported befoe, however similar bits have.

thanks, in advance, for your help.