As you know, you can limit the number of emails any account can send, per hour, in WHM. Just click Tweak Settins, below Server Configuration. But, how do you assign a different value for an individual account, different fro the value assigned to everyother account? You might want to give a certain account a greater limit. Or even restrict that account’s hability to send emails.
SSH to your server. And open the file /var/cpanel/maxemails. Then just add the code:
domain.com=100
This value will override the default value for this domain. So, if you assigned a 2000 limit in Tweak Settings, domain.com would have a limit of 100.