German hoster united internet. The few people I know with those addresses receive a signal message.

That worked like a charm for me, but some strange German mall hoster demanded the blood of an unborn unicorn or something like that for it to work.

I managed to get my mails through 95% of servers I’ve tried, and after evaluating the 5% that didn’t accept my mail, I just realized they can suck my man-tits. But maybe those 5% in your case might be recipients you value.

I’m poking my eyes out just to be safe

Oh, so now they realized how sideloading works after they bought phones with the app pre-installed.