I'm trying to get my email server to encrypt the connection between my email server and others. It currently can connect via TLS to itself but it doesn't seem to be able to connect to other servers over encryption.
In postfix main.cf - when forcing the internal encryption by setting:
smtpd_tls_security_level = encrypt
Everything works with internal TLS connections and the emails are delivered to Gmail, Yahoo, etc. But when I try to force the server to server encryption by setting:
smtp_tls_security_level = encrypt
The emails don't get delivered. They are being sent to normal TLS email providers like Gmail, Yahoo, etc. Both have the same cert.
smtpd_tls_key_file = /etc/letsencrypt/live/mail.example.com/privkey.pem smtpd_tls_cert_file = /etc/letsencrypt/live/mail.example.com/cert.pem smtpd_tls_CAfile = /etc/letsencrypt/live/mail.example.com/chain.pem smtp_tls_key_file = /etc/letsencrypt/live/mail.example.com/privkey.pem smtp_tls_cert_file = /etc/letsencrypt/live/mail.example.com/cert.pem smtp_tls_CAfile = /etc/letsencrypt/live/mail.example.com/chain.pem
What can possibly be the problem?
I'll buy a better certificate if that's necessary but I haven't read that it would be. I've tried with self-signed, Cloudflare TLS, and Let's Encrypt certificates and they all yield the same results.
Could it be something wrong with master.cf? or main.cf?