Many system admins set size limits on sent and received emails, but aren’t aware that there are actually three areas to set them in order to effectively control email size. I usually look at a user’s mailbox in Exchange to determine their specific limit and sometimes forget to check the other two areas.
Size limits should be set for the mailbox, receive/send connectors, and the transport service. If you don’t limit mail sizes, the server will likely become overloaded and mail flow will be interrupted. Admins are responsible to set practical limitations on