Having no success in setting up my email

[#1]

i am sure it is my prblem but I cannot get the emails to work. I am using Mozilla Thunderbird under Windows10. I get the message "Sending of the message failed.
An error occurred while sending mail: Outgoing server (SMTP) jctemf.plus.com is unknown. The server may be incorrectly configured. Please verify that your Outgoing server (SMTP) settings are correct and try again." so what am I doing wrong?

[#2]

@JohnCT1 The outgoing server should be relay.plus.net

Thunderbird has tried to 'guess' your outgoing server settings and unsurprisingly, got it wrong

[#3]

Sad to say that does not work either, however thanks fo the reply.

[#4]

It's definitely relay.plus.net . For info the complete set of settings are here https://www.plus.net/help/email-guides/how-to-set-up-plusnet-email/