[camgunz]

I don't want this to turn into a big support thread, but I'm always surprised by this stuff. It's not like the algorithm has some case for small services like this, like Google's spam detection is heavily based on "you sent lots of messages, they're very very alike, significant numbers of users marked them as spam", because that's the actual spam problem. Source: I've worked on political campaigns. I'm not saying you did anything wrong or incorrectly, just that I'd love to know what was really going on.

[jayski]

Aside from SPF, DMARC and DKIM, there's the concept of "pre-warming" an IP.

Where you gradually send more and more email throughout a few weeks until you have enough good reputation to send your entire volume. This is the part that's outside of normal configuration and takes more time.

In my particular case I was trying to move a system that sends about 5million legitimate emails per month (notifications for a lot of customers) - off of AWS onto a self hosted solution.

We spend about 2k per month just on sending emails and I thought if I spent a few days on it we could save that money.

Unless your IPs have built a reputation it's not going to work. I could gradually migrate volume, monitor the bounce rate, adjust, etc. But that was more work than I could afford to put into that project. I also couldn't risk getting emails sent to spam while I experimented.

https://www.twilio.com/docs/sendgrid/ui/sending-email/warmin...

[camgunz]

Ah so you were a bulk sender. Yeah that's pretty fraught; AFAIK for Gmail you have to follow their bulk sender guidelines [0], which is a pretty long list of things to do. Not impossible though.

But, again most people aren't sending 5m emails a month. They'll be totally fine setting up their own email server.

[0]: https://support.google.com/a/answer/81126?visit_id=638526753...

[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