Forbidding users from using another smtp server

[chanklish]

hello
i have several accounts in my whm that all uses my server as email server
it is working normally without any issues with spf,dkim and dmarc set .
lately i found several users using other smtp server in their outlook , i enabled smtp restrictions but nothing happened ..they kept sending emails ( and receiving errors from the dmarc in return)
is there any way where i can force them to use my smtp by cpanel ?
thank you

 

[cPanelMichael]

lately i found several users using other smtp server in their outlook

Hello,

Could you provide more information about how they are configuring their Outlook client? For instance, are they sending email using another email host?

Thank you.

 

[chanklish]

Hello,

Could you provide more information about how they are configuring their Outlook client? For instance, are they sending email using another email host?

Thank you.

hello Michael , we are using pop on microsoft outlook , smtp and pop server are my vps's hostname.
they are using other smtp service like smtp2go per example and changing the smtp server + username in their outlook account page

 

[cPanelMichael]

they are using other smtp service like smtp2go per example and changing the smtp server + username in their outlook account page

Hello,

You can't prevent them from using a third-party server for SMTP in their email client settings. However, you could prevent the SMTP2GO IP addresses from authenticating with the cPanel server in your firewall or via the "Blacklisted SMTP IP addresses" option in "WHM >> Exim Configuration Manager >> Basic Editor".

Thank you.

 

[chanklish]

is there a way to add all IP addresses to the blcklisted smtp ip except my own ? like XXX.XXX.XXX.XXX!

 

[cPanelMichael]

is there a way to add all IP addresses to the blcklisted smtp ip except my own ?

Could you provide more details about which connections you'd like to block? Is this for all incoming SMTP connections to the cPanel server?

Thank you.