Is it possible to send emails when all account are offline, i.e., only SMTP traffic but not IMAP traffic?

I need this option, since my mobile provide offers free email download (via IMAP) using a APN configuration, but to send the email I'd like to use another network configuration which is cheaper to make SMTP connections...

The only problem is that if I put all accounts offline, then start replying email, then switch to the other network config and finally send the email (by going online), chatter keeps trying to connect to the imap server as well... causing useless traffic (which is charged by my mobile account...)