<human>: No, I'm not Emily Osment.

So I know these two guys, Frank and Bob. Frank has a girlfriend named Emily. Bob REALLY hates Frank, because for whatever reason Frank's existence annoys Bob, even though Frank does nothing to antagonize Bob. 

Now recently Bob has been impersonating people that Frank knows in order to harass him. Bob made a Facebook account impersonating Frank's mother (whom later found out and had it deleted). Frank confronted Bob (over the fake mother's account), and Bob told him that he and his friends are going to sleep with Emily. Other times, Bob has been threatening Frank with text messages, facebook messages, and other methods. Bob has even gone as far as to physically harass Frank by leaving 'things' in his mailbox and do other stupid pranks which have annoying Frank's parents. 

Frank tries to ignore it, but Bob's threats have been emotionally hurting Emily and the people that care about her. I don't want to see Emily or others being hurt by Bob's stupidity any longer, and I have proof that Bob is behind all of it. I have asked Bob multiple times to stop, but he continues to do it 'for the lulz'.

Can you summarize the given text in a few sentences?
<bot>: Bob indirectly and physically harasses Frank using empty threats to Frank and his girlfriend, and will not stop even though having been reasoned with. What can an outsider with proof do in this situation?