[BlueOnyx:24021] TLS handshake failing in Sendmail

[Ernie]

I am having problems with emails for certain domains getting stuck in the
mailq with 5210R. Not had this error in other BX versions.

The server is using a Letsencrypt certificate, and the visite has it's own
Letsencrypt certificate. There is only one visite on the server. Most users
are sending via smtp AUTH.

The error says:
 Deferred: 403 4.7.0 TLS handshake failed

I can get around it by adding a TLS exemption in /etc/mail/access for the
domain eg.

  Try_TLS:qld.gov.au NO

But I can't be sitting there all day looking out for handshake failing
domains to bypass. I would like to diagnose the problem, but don't know
where to start. Any suggestions?


- Ernie.