Yes and no. If the entire content of the email is something like "Can you please add me to the new repository for X?", I have no problem with that being the sub

Yes and no. If the entire content of the email is something like "Can you please add me to the new repository for X?", I have no problem with that being the subject line with a blank (or "Thanks!") body. I'm with you on paragraph-style subject lines though.