Thank you for your post.
If the Event.log shows the backup schedule completing and no email was received, verify the SMTP server was up and running at the time the schedule completed.
To help narrow the cause, create a test script that simply performs Send Mail, captures the error code, and adds it to a table along with the date and time. Create another schedule that immediately executes after the backup schedule. If you are not receiving the test emails and backup emails, then check the error codes in the table during those times. If you are receiving the test emails but not the backup emails, consider recreating the schedule.
Thanks for the info.
I have created a script and sure enough the emails failed again today and the test didn't come through either.
I have now changed to a different SMTP server and both backup and the script emails have worked again. Based on this I have to assume that the SMTP server has been the issue. Something I wouldn't have thought as it is quite a big company and I was expecting them to have a reliable service.
I will keep monitoring it for the next days and will report back.