Hi, >Today, though - which may be unrelated - it prompted me to check the >certificate, which weirdly seemed to belong to my VPS provider; it >wasn't the one configured in dovecot. > >Has anyone else seen either of these issues? My VPS provider hasn't >come >up with any ideas yet.
They have a very clear idea - they are snooping on your TLS, and that doesn't happen by accident. It might be a sad accident with a firewall, but they should fix that in no time. If not, you are best off finding a new provider. -nik