I've received many letters of that nature, usually from someone claiming to be a service member. One dolt my age (I'm 57) claimed that he was a Captain of the US Corps of Marines. He supplied me with a photo of his Illinois Drivers License, issued Last Name First Name Middle Name. He said his last name was Middle Name. Had this been true, he would have been at least a Lieutenant Colonel on the short list. If he was just a Captain, he would have been RIFed (Reduction in Force) for failure to advance.
My advice to you, should you receive mail of this nature, is to ask for:
1. His Name and Rank
2. His Serial Number
3. His unit and APO/FPO address.
and claim that you want to use Snail Mail to prevent electronic footprints.
They'll usually claim that this information is classified (it isn't) and you'll never hear from them again.
BTW, I'm a Veteran, so scams like this really P*SS ME OFF!