I recently got a new computer and set up my Thunderbird account on my new computer using the same settings from my old computer. I can receive mail but I can not send mail. I get this error message when I use the SMTP server Sending of the message failed. An error occurred while sending mail. The mail server responded: <gregc567@icloud.com>... Relaying denied. IP name possibly forged [209.206.90.114]. Please check the message recipient "gregc567@icloud.com" and try again.

I've changed the outgoing mail server to smtp.paonia.com from mail.paonia.com and it hasn't fixed the problem.

See https://kb.mozillazine.org/5.7.1_Unable_to_relay for potential problems.

Is your ISP also your email provider? Are you connected to the Internet using them?

Thanks, but I looked at the web page and did not find a solution to this issue. No, my ISP is not my email provider.

Any other ideas?

This can happen if the sending email id and the email id on the SMTP server do not match. This can also happen if secure authentication is required, yet not provided. Possibly, if you post the screenshot of SMTP server settings, some ideas may surface. Thank you

Thanks. I ended up setting a new existing email account using imap. Seems to be working now.

So what are the differences between the two outgoing servers in outgoing server (SMTP) the old and the new?

Nothing as far as I can see. It looks like the same port # is being used. I am far from being tech savvy.... In situations like this, I just move from one proposed solution to the next until the problem is solved. or not.