Been using Zimbra for a while now, but been checking it out for a few years. Happy with it so far but we're only a small installation of 14 accounts.
Since Zimbra seems to support SSL/TLS on all aspects of its services I thought I'd start looking to see if there was a way to ensure security on the inbound mail channel, port 25.
I thought there might be some sort of protocol like SMTPS but it appears that Postfix supports the STARTTLS command.
Is this supported in Zimbra by default?
I realise this isn't e-mail encryption in the PGP sense, but it would be cool to know there's an encrypted channel there if an external MTA asks for it.
For example an external MTA is configured to offer TLS to the receiving SMTP server, eg: Zimbra.
Does Zimbra accept incoming STARTTLS requests?