I found that is Bluehost's IP address, banned in four places, spammers, not me of course. Seem to be sorting things out :)
Switching to Thunderbird seemed to fix the issue.
So much for paying premium for Microshit 365
I am a little clueless about what is going with my email.
I do have a private email hosted at Bluehost (where my domain is)
Separate names with a comma.