Cannot send emails from Tiscali account

I have an account with Talktalk and two with Tiscali. The Talktalk address works fine but the two Tiscali addresses will not send emails although they do receive.

The error meassage is:
Task '*******@tiscali.co.uk - Sending' reported error (0x800CCC80) : 'None of the authentication methods supported by this client are supported by your server.'

So I guess this is definitely a talktalk issue. The two accounts used to work fine and I have changed nothing in MS Outlook 2007.

Please get this sorted. It is most frustrating.