Question : archiving sent emails using postfix

We've setup a postfix based mail gateway that relays emails to our mail providers mail server.

the idea is so that we can backup (keep the incoming & outgoing emails of each account) in our own hard disk so we don't have to be limited by our providers' space limitation.)

We've setup a squirrelmail access to the postfix system also.

So far it worked for this scenarios:
1. All emails sent using squirrelmail are kept in sent folder
2. All emails received to the account is kept in the inbox folder.
3. All emails sent using ISP's webmail are kept in sent folder (using fetchmail and sieve)

The fourth scenario is the part that hasn't worked:
4. Emails sent from thunderbird on a client logging on to our relay server are NOT kept in the sent folder of the server. It is kept by the client's thunderbird, of course, but it is not showing on the server. (Or more accurately: it is not showing in squirrelmail's sent folder. I'm pretty sure that its' also not in /home/mailuser/INBOX.Sent/ folder but I don't know how to properly find an email on that folder)

Answer : archiving sent emails using postfix

If you are using POP3, all messages sent through Thunderbird or Outlook, will not be saved on the server.

The only way to save send messages on the server is using IMAP instead of POP3.

http://www.st-andrews.ac.uk/media/Configuring_Thunderbird_for_IMAP.pdf