This is all getting a bit weird

Received through the post two days ago:

Stop the blog
Stop the project
Stop dragging up painful stuff from the past

Written using cutout newspaper letters, I kid you not. No signature (obviously). Is this a threat? Am I supposed to take this seriously? What's going on here?

Since the person who sent it is obviously reading this blog I will say this. If you want to say something, say it. In person. With reasons. Otherwise, surely you don't think I'm just going to interrupt a five-year project on the basis of one daft letter?