You can use spam filter to block emails by size.
Login to your DirectAdmin account.
Email Managersection, click on the
Spam Filtersicon or type “Spam Filters” in the
Navigation Filterbox and the option will appear. Click on it.
Under “Block By” from the
drop-downmenu, choose the
Under “Value”, choose
Sizein KB or MB and enter your value.
Click on the
If you have chosen size in MB and have entered the value 5, for example, all emails exceeding 5 MB in size will be blocked.