I believe it is a form of protection for the server. It has happened to a few players. Let us know if it happens a lot.
From what I understand, being kicked for "Sending too many packets" is triggered by doing too many actions/events too quickly within a small time period (similar to being kicked for flying by an anti-cheat plugin). This happens a lot when you have a bad connection or are experiencing lag, and you join a server "too quickly".
Can you be more specific about "a lot"? Maybe you could keep notes for a short time about the server and time when it happens to you.
Ok next time it happens I'll write it down, I'll reply soon and say how many times it happens. It's happened about 5 times today
This happened to me too just now- I had just connected to the server, and it immediately kicked me to the lobby for the same message (its only happened once so far to me) Revenge of the Proxy.
Guys I think I know how this happened... I was lagging so I clicked the sign multiple times to connect, like Spam Clicking... Resolved now, just be patient this can be locked