Forum Hundreds of spam private messages
 

I recently had a couple users including myself get spammed by a few members on my site. What is happening is when a user sends a pm to someone, from time to time the message gets resent over and over again, sometime several hundred times. I received a pm from a member and the message was sent 900 times. This does nto happen all the time and has only happened to a few members but could turn into a problem.

Any ideas to the problem? I have not added any mods to the site in some time and currently running the latest version of 4.2