I've a Ubuntu 9.04 server installation which is hosting a small number of websites (currently two, and will remain in single figures). The email requirements for the server are very limited - to send outgoing emails and forward all incoming emails to a mailbox on another server - most likely Google.
I've installed postfix and the outgoing mail is working fine. How do I configure Postfix to forward all incoming mail? If I send it to a googlemail address are there any special considerations? Finally how difficult is it to incorporate basic spam filtering into the forwarding mechanism?