Email not sending after update

I have a plugin that updates the authorised status of a database record. I'm trying to get universal email to send an email after the update is performed. I have removed the redirect from the multiple update server behaviour and when I check the database I can see that the records are updated successfully.
The redirect is set to occur after the emails have been sent and this redirect works. However, no emails are arriving at any of the addresses I specify.

I've tried this using both dynamic email addresses from a recordset and a single static googlemail email. Both the update and the email use the same trigger i.e. once the update button is pressed.

I've looked at other threads with similar problems, but I still cannot get the email to arrive?

The plug-in I am using is attached