Sometimes while sending email from Horde, it takes to long and at the end it
shows below error message :
“Horde error :Failed to set sender: email@example.com [SMTP: Failed to
write to socket: not connected (code: -1, response: )]”
Be sure that “SMTP_ALLOWLOCAL” option is enabled in CSF configuration file
(/etc/csf/csf.conf). It should be enabled if you want to allow local
connections to port 25 on the server (e.g. for webmail or web scripts).
SMTP_ALLOWLOCAL = “1”
Make sure that “SMTP_ALLOWLOCAL” has a “1” entered in the box next to it.
Restart the CSF firewall once this is done.