I have about 10 servers running on DO, one of them for email. I do everything to look trustworthy but my email still ends up in spam so I'm assuming a bad IP bl

I have about 10 servers running on DO, one of them for email. I do everything to look trustworthy but my email still ends up in spam so I'm assuming a bad IP block range. Anyhoo, I also do a bunch of DNS stuff with DO. Haven't had issues in the past...is it 5 years I've been with them? I have a friend who works at Vultr so I'm testing them out for a side project.