How to get caught using multisend

[buddysievers]

Hey and hello,
i was wondering how server admins/GMs can caught you using multisend?!
Usually you get caught by sending packages which they analyze and see that they are not comming from your client if im not wrong.
So how do they see that you sending commands to your client which then sends legit packages to the server?
Or does multisend works different and sends fake packages?
Sry for this stupid questions but im just curious. Thx in advance!