I've had no problems, but just recently I had two separate emails be ignored by GMail users. Some followup communication suggests to me the mails were never seen, but I am unable to find out if they ended up in the spam folder or not. (At least one other GMail user did receive a recent mail from me.)
That has shaken my confidence in my email setup, which has run without issue for many years now.
And I don't have any end-to-end tests, other than seeing people reply to my emails. I occasionally check my domain on various blacklist checkers.
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.
For me the biggest hurdle is absolutely not the manual setup process or the need to adjust things from time to time. Rather, it’s the fact that there doesn’t seem to be a simple, quick and reliable way to tell if my setup actually works.
How can I be sure that my email actually reaches its destination? That there’s no error in my DNS entries? 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?
I really hope I’m wrong and it’s possible to implement some kind of monitoring that tests my self-hosted setup and alerts me by SMS if something’s wrong with it.