Is it fair use of Letters forum to say that you got note delivered to upper/lower by some beggar/boy/unnamed unimportant person, or do you need to separately get DM to RP it out. This is in cases where your actual character is prevented from travelling there (or does not want to).

It does seem natural that having some boy do your errant would work, and that it would tax DMs much if it was RPed every time.

Just something I pondered about, what would be the best protocol here.

I typically pay a child begger one coin and RP that he should take a few letters for me. These beggers are fairly commonplace. I guess its fair to assume that a DM could step in and say the begger never got where he was going before a response was made, in which case, you could always just pay a different begger.

It's fine to send letters and assume a NPC ran it over.