cant send emails

[#1]

i cant seem to send any e-mails from outlook express or thunderbird what am i doing wrong, can anyone please help
regards
          kev

[#2]

sorry i forgot to say that i get this message
The message could not be sent because one of the recipients was rejected by the server. The rejected e-mail address was 'xxx_xxxx@o2.co.uk'. Subject 'subframe', Account: 'mail.plus.net', Server: 'relay.plus.net', Protocol: SMTP, Server Response: '550 relay not permitted', Port: 25, Secure(SSL): No, Server Error: 550, Error Number: 0x800CCC79
jim:green email address removed for security mod:end

[#3]

Is it just to 1 address that you're having problems sending? It looks like that address isn't valid which is why you're seeing the bounce.

[#4]

no it is all e-mails i try to send. i can recieve e-mails ok but can only send from plusnet webmail

[#5]

It is just possible that you have set up SSL which isn't supported

[#6]

i dont wish to be thick but what is ssl and how do i change it

[#7]

What does http://usertools.plus.net/@gateway say?
B.

[#8]

http://www.plus.net/support/email/setup/outlook_express.shtml
at  the bottom of the page under advanced