I have had several issues with my personal .me domain. I’ve attributed it to poorly configured systems that consider it risky simply because it’s the TLD for Montenegro - despite it having millions of registrations for other legitimate purposes.
As an extra bit of authenticity I've been smime signing my sent mail. Not encrypting, just signed. I figure that something no spamer is going to do and I’m hoping any spam filter will look at and pass it. Assuming they don't ignore it and make it a waste of time.