this seems like a bug to me, so I'll just drop a notice here.
While commanding, very often when I fight a boss down in its area, I can write just a few lines in mapchat (doesn't matter if some time apart) and get "your message was supressed due to excessive messaging", which makes coordination with other commanders rather hard just telling the % and get supressed the next message.
For me it happens a lot of times at Hablion and Wiggins.
As soon as I WP and stay center I can use mapchat in a normal way again. Only happens when bosses are up.
This happens to more commanders around and doesn't seem to be intentionally.