I'm getting this connection string error in the RoundCube logs:
IMAP Error: Login failed for xxx against localhost from xxx. Empty startup greeting (localhost:143) in xxx/public_html/program/lib/Roundcube/rcube_imap.php on line 211 (POST /?_task=mail&_action=refresh)
I've looked around for days and found all types of suggestions and I've done most of them. I've changed my SSL/TLS certificate and ports, checked my network firewalls, etc.
The big issue for me is that I don't get this message all of the time. I get it about 10% of the time, but I have 50 users that are all trying to use RoundCube all day and they are each sporadically/intermittently getting this message which adds up to hundreds throughout the day. When they do, the site doesn't work, but if they wait or refresh enough times, it does.
It feels like a resource issue, but resources seem to check out fine on the VirtualMin and Apache Server Status screens. I'm at a loss as to where to check next to troubleshoot.
Other notes:
- Fail2Ban is installed, but I have whitelisted the appropriate IP addresses.
- MariaDB is used, I do not have "require SSL" turned on, in the database and I've increased the maximum connections up to 300 from the 150 default.
- This server is strictly email, so there are no other websites eating the resources. It's using 4 core CPU and 8gb of Memory in a virtual environment.
- RoundCube is installed in the "webmail" subdomain with SSL redirection turned on and everything tested to be working from my environment. But, it continues to sporadically fail for my clients from all 8 of their locations.
- Email clients are not showing any errors that I know of - just RoundCube.
- Apache Server Status -
Server load: 0.23 0.31 0.26; Total accesses: 700 - Total Traffic: 3.5 MB - Total Duration: 97627; CPU Usage: u1.28 s.69 cu0 cs0 - .112% CPU load.
Some Logs I've looked at:
/var/log/mail.log- I can see some SSL_accept errors in their, but these seem to be more from dovecot/postfix in trying to send/receive email./var/log/apache2/error.log- Not showing any errors.syslog- Only showing connections, no errors.
Any suggestions/feedback is appreciated!
