Judicial complaints

I received an email from forummotion stating that a complaint had been filed against my forum for copyright violations by a competetive forum. However, when I contacted the administration of that forum, they did not lodge the complaint. Also, when logging into my admin panel, there is no record of any complaints past or present yet the email specifically mentioned this other website. How do I find out the details of this complaint as we take these things very seriously on BOTH forums and if someone is making accusations and claiming to be someone else, we need to know about it in order to prevent it from happening again.