The first thing to find out is why those emails are failing. The logs will help -- you may have to turn some to trace .
Things to check:
- Is the alarm actually triggered?
- Is the email getting sent from Ignition?
- Did Ignition get anything useful back from the SMTP server?
If the alarm is getting sent to the SMTP server, then Ignition has done all it can. Unfortunately, most SMTP servers don't give us good information on what happens to an email after they get it, and there are all kinds of ways emails can fail after that point.