[snksnk]

Just relay it out via a trusted host, in addition to setting up DKIM, SPF, etc.; that solved all the problems for me. My email server is working excellent for many years now (OpenBSD, OpenSMTPD, dovecot) with Rainloop as web-based frontend.

[sfilargi]

I have DKIM, SPF, etc. but still gets caught by spam. What do you mean by "trusted host"?

[snksnk]

An email provider that is not blacklisted and allows relay. I currently use my ISP for that.

Taken from my smtpd.conf:

  table secrets { mylogin = [email]@ziggo.nl:[pass] }
  accept tagged DKIM for any relay via tls+auth://[e-mail]:587 auth <secrets>

[sfilargi]

Oh, I see, thanks!

It kind of defeats the purpose, since now the third-party will be able to read all my outgoing emails, and have control over them.

[tux1968]

You're transiting over their network anyway -- the jig is already up even without relaying via their gateway.

[justinclift]

Connecting directly to the remote (non-ISP) mailserver with TLS shouldn't reveal any message contents.

Relaying via the ISP's mail server though (even with TLS) seems like it would disclose the message contents.

[phaer]

Is DMARC included in your 'etc'? I think thats needed for gmail these days. If rdns, dkim, spf and dmarc are there, try checking your IPs reputation (senderscore) that could be it.