Postfix: user unknown in virtual alias table

[stuorguk]

My gentoo server has started rejecting outgoing mail.

"user unknown in virtual alias table"

The server hasn't been rebooted for 3 months, and noting has changed since. Incomming mail is fine. I have just rebooted the server, and it's the same.

Any ideas?

[stuorguk]

Problem solved.

It seems one of the domains I was hosting has moved nameserver, and was inaccessible. I added it to the hosts file.