MobileMe and Mac Mail issues

This becoming so frustrating I'm actually considering binning my MobileMe subscription (I can't believe I said that). I'm running OSX 10.5.6 and recently opened a MobileMe account, excited that I would be able to sync all my mail, contacts and calenders, up in 'the cloud'. If I access my account through the MobileMe website, all is good, but as soon as I try to send an email from my Mail app on either my G5 (or G4 iMac at home) it gets bounced back to me with the following error message:

Cannot send message using the server smtp.me.com:name_surname
Sending the message content to the server failed.
Select a different outgoing mail server or click 'Try Later' to leave the message in you Outbox until it can be delivered.

I've checked all my settings and it says that I am logged on to the server, I even have emails coming into Mail for this account, but I cant send one out.

Why is this?

Do you have "SMTP server requires authorization" box checked under advanced SMTP settings? You also want to select "Use same settings as the receiving server" option.

I seem to have solved the problem by deleting the account from the System Preferences > MobileMe panel then re-creating it. I can now send emails from my Mac Mail application! Very strange though as it was fine a few days ago.

I had something similar happen actually - but it wasn't the email, instead it was the iDisk and had to log out of mobile me and reconnect to it and ever since then no problems.