Mail relay error preventing notification to all recipients

I added a new recipient to an alert notification today, with a different domain than we normally use. I started getting SMTP 550 “Unable to relay” errors in the console. The problem is that there were 2 recipients set up for this notification and the above error stopped the notification system from sending it to either.

I do realize the underlying error is a mail server issue and I’ve worked around it by using a different mail server.

This is on Ignition 7.5.4.

The problem here is that the emails will get sent out together, and your mail server is the one stopping them. Unfortunately, there’s no way to split the addresses apart. Your solution to use a different mail server is the best one.