Since I am stuck with AT&T 2G on my N900, whenever I get a public Wifi I connect to it. In Email Settings, I have set "Update Automatically" and "Update When Connected via --> Wifi". Because this doesn't say which Wifi, the emails are synced on all Wifi networks including public (unencrypted) networks.

So my questions are:
1) Are the IMAP and POP3 transactions safe on a unencrypted Wifi connection?

2) If no, is there a way to specify which Wifi connection (only) to use for automatic syncing of emails?