Also check that the mail account types are the same on the macs, it may be that one is POP3 and needs different setup or something changed at the Tiscali end. You may find instructions for setting up Mail on
Tiscali's site if you are lucky & want to double check.
You could disconnect the ethernet & try wifi on the MBPro to see if it is the issue, seems unlikely since it should be connecting to the server to get the password refusal, and your iPhone will be on your WiFi too?
If it fails to fix it, let us know what versions of mail you have.
Re:co