This is where things can get frustrating… you run this blacklist check and you are green across the board, yet you continue to experience those darn MTA reputation warnings! First off, what the heck does MTA stand for? MTA is the acronym for Mail Transfer Agent and it’s nothing more than a fancy term for your server that sends out your mail. So in case you thought MTA was some kind of dedicated Microsoft technology that you can deal with directly, it’s not… it’s just a general term for the hardware doing your email sending. There are several databases and companies that calculate this reputation, and some ISPs rely on these companies to provide them with tolerance scores to reject possible spam.