

The domain name doesn’t matter at all. The really important thing is the IP of your MTA (the server sending mails). Eg. if it was previously used to send spam you need to get a new one from your server provider, as it will be blocked everywhere. Also the server configuration needs to be good. Use dkim, dmark, spf, mta-sts, etc.
Logic doesn’t work for people trapped in a cult. They can claim whatever they want and don’t need to admit anything, it doesn’t matter. 😔