Mail limiting feature is available in cPanel >> Tweak settings >> Mail
Max hourly emails per domainTweak Settings >> MailThis option allows you to limit the number of messages that the domains you own can send.
Count mailman deliveries towards a domain's Max hourly emailsTweak Settings >> MailThis option allows you to count messages sent to Mailman mailing lists against an account'sMax hourly emails per domain limit. By default, this setting is Off.
The percentage of email messages (above the account's hourly maximum) to queue and retry for deliveryTweak Settings >> MailThis percentage is compared against the Max Hourly Emails value. By default, when a user exceeds the number of emails the domain can send per hour, additional messages are queued to be sent later. This setting allows you to specify a point at which any additional outgoing messages will be ignored.
Maximum percentage of failed or deferred messages a domain may send per hourTweak Settings >> MailThis option allows you to specify the percentage of failed or deferred messages a domain can send before it is temporarily prevented from sending mail. The percentage you specify here is compared to the total number of outgoing messages from the domain.
You can enable RBL and Spamassasin,
WHM >> Main >> Service Configuration >> Exim Configuration Editor >> RBLs - > to enable RBL
cPanel>>Mail>>Spam Assassin -- to enable spamassasin
Max hourly emails per domainTweak Settings >> MailThis option allows you to limit the number of messages that the domains you own can send.
Count mailman deliveries towards a domain's Max hourly emailsTweak Settings >> MailThis option allows you to count messages sent to Mailman mailing lists against an account'sMax hourly emails per domain limit. By default, this setting is Off.
The percentage of email messages (above the account's hourly maximum) to queue and retry for deliveryTweak Settings >> MailThis percentage is compared against the Max Hourly Emails value. By default, when a user exceeds the number of emails the domain can send per hour, additional messages are queued to be sent later. This setting allows you to specify a point at which any additional outgoing messages will be ignored.
Maximum percentage of failed or deferred messages a domain may send per hourTweak Settings >> MailThis option allows you to specify the percentage of failed or deferred messages a domain can send before it is temporarily prevented from sending mail. The percentage you specify here is compared to the total number of outgoing messages from the domain.
You can enable RBL and Spamassasin,
WHM >> Main >> Service Configuration >> Exim Configuration Editor >> RBLs - > to enable RBL
cPanel>>Mail>>Spam Assassin -- to enable spamassasin