Thanks for this info, I have done what you suggested however I still get the following error and I don't really know how to deal with it:-
Could not connect to host
www.1and1.co.uk.
The message will stay in the 'outbox' folder until you either fix the problem (e.g. a broken address) or remove the message from the 'outbox' folder.
The following transport protocol was used:
auth.smtp.1and1.co.uk
What do I do know?
Adrian