User blog comment:Edwin Shade/An Intriguing Discovery/@comment-30754445-20171119062932

Regarding the question in your final paragraph: Probably not.

When it comes to famous open problems (like Goldbach's Conjecture or the one discussed here) the vast majority of claimed proofs are quite basic. These problems attract a huge amount of amateurs and hobbyists and even crackpots, and the odds of a specific paper of this sort being "insightful" are pretty much zero. Really, your chances of finding a deep insight in a random notebook you've take from a random maths college boy would be higher.

And this is even before we consider the question of whether the letter is genuine. How would a 1994 letter find its way into a library book that was published in 1998? And didn't they have email in the universities, back than? Seems odd to me, that two mathematicians from 1994 would correspond by snailmail.

But who knows?