NAV 2016 Approval Notification Emails not sending

Hi All,

We are having an issue with Approval Notification Emails in NAV 2016.

If we manually start the Job Queue that runs the Notification Entry Dispatcher (Codeunit 1509), instead of starting it automatically from the NAS, then the approval emails are sent successfully.

However, if we start the Job Queue automatically from the NAS instead, then no approval emails are sent and the associated Notification Entries display an Error Message of "The email address "" is not valid."

Has anyone experienced this issue before?

We are using NAV build version 9.0.43402.0.

Thanks in advance for your help.

Regards,

Blair