I always ask for a receipt because of the issues noted above. I need stuff ASAP for expense reports, and there have been too many times they don't email.them. I can't find any rhyme or reason. For a while I thought it had something to do with which property I was at, but, that theory doesn't hold up anymore.
Sometimes, literally, as I'm walking out the door, I get an email.
Sometimes, it never comes at all.