SMTP security

[leonardo99]

is there a possibility to prevent that a user sends more than x mails per hour?
so that if an account is used as spammer we can nearly immediately realize it.

[Code Crafters]

There is a similar setting for Max Mails Sent Per Day (count of mails sent per day per user) and also Max Mail Sent Per Day (KB) (total KBs sent per day per user). These are both in the group settings for the group the user belongs to. There are also similar settings per IP instead of per user in the SMTP security settings.