Email cannot be sent from Roundcube and the following message is shown when attempting to send an email:
SMTP Error (-1): Connection to server failed.
An error similar to the following can also be found in the mail Exim log:
20XX-01-01 00:00:00 TLS error on connection from [::1]:34936 (SSL_accept): timed out
The Imunify 360 software contains a firewall configuration in addition to its malware management capabilities. If SMTP Traffic Management has been enabled in Imunify 360, SMTP traffic can be limited, which prevents the Roundcube services from communicating with the server locally.
- Log into WHM as the 'root' user.
- Navigate to "Imunify360 / Settings / General"
- Locate the "SMTP Traffic Management" setting
- Enable the option to "Allow local"
- Save the changes