I run a mailinabox server for almost half a year and gmail is a pita. I send an email to a gmail user and it always goes into spam. I have to phone them to unspam it but next day same thing. Yahoo mail or others dont seem have this issue because I have 10/10 on the dkim something scorecard.

Google somehow wants to force me to not use my email server. Fuck them

Do you have a residential IP?

It you don't have dmarc enabled that is for sure worth doing too.

Name an ISP that will allow non-filtered TCP port 25 traffic for a non-business account to go through.

A $5 reverse proxy with a cloud/colo IP goes a long way (so you can map 25 -> whatever you like).

It does mean your traffic is centralized through a data center, but it probably goes through one already...

i am using racknerd

It's been 5+ years since I've last used SpamAssassin, but at that time it didn't hold a candle to Gmail's spam filtering.

Also you're incredibly alienated if you think a "normal person" could manage their own mailserver. 95%+ of western people couldn't use a CLI.

Hm, personally I feel Google is cheating. While they catch also all spam they also catch a lot of legitimate mails. I have a couple of accounts at Google and one at a company which uses SoamAssasin and I prefer that SoamAssasin setup since it has way less false positives but still catch most spam.