**Edited version**: What are great examples of comprehensively archived mathematical correspondence (including both handwritten and electronic items)?

Previous version : ~~How should mathematicians archive their work-related output?~~

Context: here I'm thinking about drafts, and correspondence between mathematicians, either in the form of handwritten material or of emails. For example, I would find it fascinating to read, say, the collection of Letters that Deligne sent to lots of people over the years (and the replies) [1], or the email exchanges between Green and Tao culminating in their theorem on primes in arithmetic progression.

[1] Some have been archived at IAS https://publications.ias.edu/book/export/html/2582 but they are missing lots of others like a letter to Cvitanovic https://birdtracks.eu/extras/Deligne96.pdf or those to Bar-Natan https://www.math.toronto.edu/~drorbn/Deligne/

should..." is a bit too opinion-based(?) -- What about asking instead for examples of how people are actually doing it? $\endgroup$onlyabout stuff available online.) On an unrelated note, have you considered adding link also into the post - rather than just in a comment? $\endgroup$