A few things to keep in mind...
If a REAL company representative does not like what you are selling, they would most likely issue a takedown notice through the VERO program. If they did, for some reason, wish to contact you directly, they would most likely do so through their law firm.
And the lawyers wouldn't be hiding behind an eBay account with private listings and feedback. They would WANT you to know they were for real.
Reporting a bogus email to eBay is fine, but be sure you are clean as well. eBay MIGHT end up asking you to provide invoices, etc. to prove your items are legitimate.
In my experience, the best way to handle these people is NOT to respond at all. You cannot win an argument with them, since their goal is to scare you off.
Always check each message or email for misspellings, punctuation and grammar. More often than not, these people are younger, and they do not have the best writing skills. They THINK they are brilliant and have found a brand new, never before tried way to eliminate the competition. The reality is, they are greedy morons - they are not NEARLY as smart as they think they are.
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you can't trademark the word beanie that's ridiculous what about beanie hats? 
