I have stopped receiving emails as of early this morning from my ISY set to default mail server. Hitting the "test" button in the email section of the admin console gives me an smtp error. The last email I received at 4:32am today. I should have received quite a few since then. I hadn't touched the system between than and now, so no changes I made could have done anything.

@apostolakisl I don't use the default server so haven't switched to that to test, but your best bet is to setup a gmail account and use that so it's not reliant on the "default" server supplied by UD. Over the years they've had to implement processes to limit spam through the process, but also the volume of repeated messages going through that server probably give it a lower rating for relay points since the messages could be seen as spam (if they're identical and sent a bunch of times.

The directions on the UD WiKi still seem to work for setting up Gmail to work for email notifications: https://wiki.universal-devices.com/ISY994:Configure_Mail_Server_Settings#Configuring_gmail_Account

The other (perhaps, better) alternative is the Notifications plugin and using UD Mobile or Pushover to get instant alerts on the mobile devices.

For this specific issue it might be best to open a support ticket with UD to get direct help and to see if they see anything happening with the server and bounced messages on their side.

https://www.universal-devices.com/my-tickets

Whatever the issue was, it seems to have been fixed. I received an email today at 9:04am and did a test and it worked as well. @Geddy I am using a gmail account on a different isy and it works great. But on this one I didn't see the point since it was so easy to just click the default. I haven't had issues with it and I have been using it for over a decade. So who knows. I'm sure some server somewhere got messed up and needed to be reset.