What not to do when you want something corrected

So I got an email today from a complete stranger saying this:

[Missing person] was not a drug addict and your story about what happened is not all correct. The police also have not acquired any phone records from any phones.

This was literally all it said. There was no introduction. There was no signature. There was no information on to what exactly was wrong in my “story about what happened” (it was not the part about the phone records, because I never said anything at all about that), and no indication of how the person knew that the MP wasn’t a drug addict and that there were other mistakes in the casefile.

Why should change my casefile, disregarding the information from my other sources, just because some random person writes me an email like this? I don’t know if this person knows what they’re talking about, or if they even knew the MP. I tried Googling the sender’s name along with the MP’s to see if the sender is mentioned in any articles about him, and found exactly nothing.

I get a LOT of emails. If you have a correction to make, and you don’t know me and have never written to me before, it would be a good idea if you were to introduce yourself to me, and let me know how you know I’m wrong.

Things like “I am the MP’s friend/relative” or “I am a cop investigating the case” or “I found this article saying the opposite of what your casefile says, here’s a link to it” are helpful. This can all be accomplished in a few sentences and will make it much more likely that I’ll give you the time of day.