Same issue. Used GMX as a forwarder for many years, because we needed to send messages to more than one phone. But they discontinued the features making that possible. Then set the system up using Gmail’s mailserver with app-password, directly to each phone individually (had to duplicate messages and it really cut down on the numer of events we could track), but we still get erratic performance. Half the time the messges never arrive at all, or we’ll suddenly get a wave of old messages all at once. Didn’t matter if we were using Verizon or ATT as carrier, same poor behavior. I don’t know if its because of increased security against spam, but I’m pretty confident the probem is at the phone carriers.
Note to ELK staff: The ELK Connect app does app-based notifications. You need to do the same for M1. Doesn’t need to be a whole programmer app, just the kernel that does notifications on phones. Its becoming increasingly impossible to actually program “dumb” email to text messaging, either because you can’t get the technical details out of your ISP or the phone carriers block it. One of the best things about M1 is the flexibility to send custom notices based on any event, but we’re living on borrowed time here. An app-based notification is going to quickly become the only viable way to keep this M1 feature working.