In WHM under Tweak Settings the "Number of unique recipients per hour to trigger potential spammer notification." setting sends a notification when the set threshold is reached. There may be a user that needs a higher threshold This threshold can be manually set on a per user basis.
According to notes in the Perl module located at /usr/local/cpanel/Cpanel/EximStats/SpamCheck.pm the following can be done.
Modify the cPanel user configuration file /var/cpanel/users/$user where $user is the cPanel username.
Insert or modify the following line into that file with the desired threshold integer.
Then save the file and run the following scripts.