Symptoms
When attempting to send an email from a webmail client such as Roundcube, you are presented with the following error:
"SMTP Error (-1): Connection to server failed"
Description
This error mentioned above is typically caused by having the following setting enalbed within the CSF firewall :
SMTP_ALLOWLOCAL = 0
Workaround
Please change this setting to the following instead:
SMTP_ALLOWLOCAL = 1