[alan-hn]

I had a mail server on a linode for around a year, I tried everything I could to get google to accept my emails and it never did. I only used it as a personal email never did bulk sending. I had to switch to a hosted provider with a custom domain instead because it was such a big headache

[camgunz]

I don't have any experience with them, but you could maybe use Google's postmaster tools to debug.

[alan-hn]

I tried that, nothing helped. I even registered the domain with google and added their verification to my DNS records