This is due to an over-zealous spam filter. You can always hop on #hornetq on Freenode IRC and chat with a developer directly. My nick is jbertram.
Like Justin says this is because of the way the spam filters have been implemented. Many genuine users have been affected by this and this has been reported numerous times in these forums, but there hasn't been any response from the .org team to fix this issue. One such report is here One post per hour