If the webmail on cPanel server is giving error as bellow

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ERROR: Message not sent. Server replied: Connection timed out 110 Can’t open SMTP stream.
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If this error occurs when you try to send e-mails using webmail it is a  possiblity that the firewall installed on the server is not allowing the connections to the SMTP service

If you have csf firewall on the server please check its configuration for the parameter “SMTP_BLOCK”, the configuration file is “/etc/csf/csf.conf” 

 

If it is configured like below

SMTP_BLOCK = “1”

It is enabled thereby it will block outgoing SMTP.

Please turn it to

SMTP_BLOCK = “O”..
And webmail will start responding perfectly..

Well it did at least  for me..  hope it does for you as well…