Thunderbird outgoing email problems

[#1]

I've set up Thunderbird as per plusnet instructions and can read and (apparently) send email. However. sent email never arrives at its destination and just disappears    Sending via webmail works Ok so it looks like it's being swallowed in the webmail system as Thunderbird believes it has sent it to the mail server.
Any ideas?
Mark Enderby

[#2]

Have you tried sending an email to yourself via Thunderbird?

[#3]

Sounds like you might have the wrong email address in the Thunderbird configuration. It won't prevent you reading the mail correctly, since that uses the username and password and it won't stop it being sent, but it would have the wrong email address on the outgoing mail.

[#4]

...or possibly the wrong Outgoing Server Setting

[#5]

Also on your Account settings, make sure you have "Use secure authentication" unticked.