Do we agree that there is since weeks a very high probability to go to the spam folder of Gmail's and Hotmail's people using mailbox.org with a custom domain?
I understand that this article explains at least a part of the reason: https://mailbox.org/en/post/security-adjustment-and-deactivation-of-certain-mail-functions
But for the moment I still have issues to get my emails read by my receivers.
Do some people use another privacy-friendly provider which doesn't have these issues?