> That an obscure email service used by one of my clients doesn’t whitelist only major email providers? Can I be sure that things fail loudly when they don’t wo

> That an obscure email service used by one of my clients doesn’t whitelist only major email providers? Can I be sure that things fail loudly when they don’t work? These are simply symptoms of FUD. Using that line of argument, you'll always end up with the biggest players, even though there is no technical reason to do so. > to implement some kind of monitoring that tests my self-hosted setup and alerts me by SMS On the other hand, how would you check that $BIGPLAYER's mail setup works with any other email service? You can't. Could you blame anybody at $BIGPLAYER? In a free service: No. So why would you want do put so much higher standard on your own setup than on $BIGPLAYER's setup? Just to be able to say: "Oh no, available technology is not good enough, I'm staying with $BIGPLAYER." This doesn't make any sense to me.