You’re definitely on the right track here! You’ll typically see this RoundCube error when there’s an issue with the Dovecot service. It appears that we’re missing some crucial information from those log messages (they appear to be truncated), so we’ll likely want to review your Dovecot logs for more information on why your ssl_protocols value is coming up as invalid. To discover the location of your Dovecot logs, you should be able to use this command:

doveadm log find

Once you’ve located the appropriate log file, you’ll want to look for these particular entries to determine the cause behind this error. It’s possible that this is related to SSLv2 no longer being supported in ssl_protocols. I believe that you can review this setting in the following file:

/etc/dovecot/conf.d/10-ssl.conf

In Dovecot v2.3, the ssl_protocols setting is replaced by ssl_min_protocol, so you may want to check for that setting instead. You can determine your Dovecot version by using this command:

dovecot --version

Thank you so much for your help!

We are running dovecot 2.2.27. When I check the /etc/dovecot/conf.d/10-ssl.conf file the ssl_protocols line is commented out.

SSL protocols to use

ssl_protocols = !SSLv2

Should this line be uncommented?

Then when I view the mail.log file it gives me this error:

dovecot: pop3-login: Fatal: Invalid ssl_protocols setting: Unknown protocol 'SSLv2'

and

dovecot: imap-login: Fatal: Invalid ssl_protocols setting: Unknown protocol 'SSLv2'

I figured this one out!

So the config file I needed to be looking for was

/etc/dovecot/dovecot.conf

This line in the file had both

ssl_protocols = !SSLv2 !SSLv3

so when I removed the !SSLv2 and restarted the dovecot service, I was able to successfully login to RoundCube.

So it looks like dovecat is now working but we cannot connect via pop3 to the mail server now.

Does anyone know what might be causing this issue?