It appears that Mark Sapiro email@example.com said:
FWIW, a couple of my regular correspondents have said that DO generally does not have a great email reputation, and that they're moving lists to other platforms.
That's probably correct, but are there other cloud VPS providers that are better at hosting MTAs?
DO really is bad, and I block most of their IP ranges, poking the occasional hole for mail I really want.
There are better hosting providers. There are some that don't enable outgoing mail unless you ask and some that do some sort of filtering on outgoing port 25. I use tektonic.net which does the latter but the filters are mild enough that outgoing STARTTLS works fine.