Cannot send emails from Mac Mail

[ozone]

I don't know what's going on with my Mac Mail account. I cannot send anything out: it's stuck in the OutBox. It keeps saying or referring to choosing a valid server (but I've got iCloud listed). I can receive emails, I just can't send anything out. And it seems like all the necessary boxes are checked off, and despite searching the internet, I can't find any sort of solution.

Any suggestions appreciated. Thanks.

 

[bogdanw]

If enabled, try to disable iCloud Private Relay & Hide IP Address
https://support.apple.com/102022
https://support.apple.com/guide/mail/mlhlae4a4fe6/mac