Tim:
The Opera mail client was useless for that sort of thing. It would bog down for twenty minutes or more, just opening the program.
Guillermo Garron:
I have found this on the opera help page
If you are using IMAP with Gmail, go through the following settings after setting up your IMAP account, to optimally sync your Gmail account with Opera Mail: Go to Mail > IMAP Folders. Under Accounts select your Gmail account. Now, uncheck the following folders: [Gmail]/All Mail [Gmail]/Spam [Gmail]/Trash Click Ok
So, you can unsubscribe from any folder you may want, and therefore, it will only sync those folders you want it to.
hope that helps.
I gave up on it long ago, but it might help someone else. I was using it with a local IMAP server (Dovecot on Fedora Core 4). Unsubscribing from folder that I wanted to use wouldn't be a solution, though.