SMTP Tweak - Advantages & Disadvantages?

ES - George

Well-Known Member
Jun 12, 2011
cPanel Access Level
DataCenter Provider
I decided to spend a few hours going through every single option in WHM and seeing if anything needs changing, asking any questions I may have, etc to help benefit my server's performance and stability.

SMTP Tweak - I've seen the option before, however never really looked into using it. Would you say it's good practice to have it enabled? From what I can gather, the advantage is that it stops people from abusing the mail server. I was just wondering if it has any benefits, i.e. effects on the server load, issues with mailing, etc.

Thanks very much.


Well-Known Member
Aug 19, 2010
Gods Own Country
cPanel Access Level
Root Administrator

Yes, it is a good practice to enable this feature. If you enable it, only restricted users can open a direct SMTP socket to a remote host which will enforce the normal users to use exim/sendmail to send emails; which will prevent the vulnerable scripts from abusing your server which will try to send emails in a similar fashion.

To know how its working, just enable this feature and allow shell access for a cPanel user.Now run telnet <any remote SMTP server > 25 and you can see that it won't reach the destination server and remains "connecting..." state....

If you have CSF installed on your server, pleaes disable this featre in WHM and enable it in your CSF conf instead.

Thank you,