Also I think this is a really long spam of the spacebar, not the "Enter" key, since it would send a reply.
CJ/Brock should make a function where players cannot enter 10 or more of the same characters in a single chat, say the same message for the next 5 seconds, and type past like no more than 200 characters.
Oh gosh no, that would be too overkill. You're going to say 11 es in 140 characters far too many times.
There's already a character limit for messages
Also, users can type enters in an external program and paste them into their ingame chat, so they don't have to use spaces (and the char limit wouldn't let them do so much wiping anyway with just space)
As for same message, sometimes you need to say 'yes' twice or 'ok' or even use smiley faces twice in a short space of time to respond to people. Perhaps a block on repeating a message 3 times would be good, but I think allowing mods to police what is and isn't spam would work much better.