You really just got to send more e-mail and then ask your friends to mark it as "not-spam" .. #spamhaus is probably the least you have to worry about. I run my own e-mail server as well:

https://battlepenguin.com/tech/upgrading-opensmtpd-6.3-and-running-e-mail-in-docker/

...and I wrote this back in 2015 on the whole "marked as spam" issue:

https://battlepenguin.com/tech/how-google-and-microsoft-made-email-unreliable/

There's an older article that's gone now (you can sometimes find it in an archive) titled "The hostile e-mail landscape"

After a few years with my e-mail on Hetzer, most of it seems to get through now. mail-tester.com is a pretty decent checking tool.