We have an instance of Sitecore 8.2 update 5 using XDB cloud and EXM hosted in Azure using PaaS AppServices.
I am testing EXM and trying to send test email campaigns from our CM instance. However even through EMX reports the campaign has been successfully and sets the status to “sent” zero emails are actually sent.
I have uploaded a test CSV document with the first name, last name and email of all the developers in my team, a total of 9 contacts, and I can see using Robo mongo these contacts are in the analytics set in XDB Cloud. What’s more confusing is that I can sent a test preview message from the Review tab. That works fine.
Trawling through Application insights, I can see a common error...
6756 16:53:04 WARN Unhandled exception thrown while processing task '0xBB3AF911DC384345AA2C16966CF4BF17' **from task pool 'dispatch_failed_task_pool'. The task has not reached the maximum number of attempts to process a failing task and is postponed.** Exception: System.ArgumentException Message: **Null ids are not allowed.** Parameter name: **contactId** Source: Sitecore.Kernel
The contactID parameter is odd as the contacts use the email address and the contact unique identifier.
I have an ongoing support ticket open with Sitecore but they are struggling to resolve this.
Can anyone shed any light on this?