This article will guide you through detecting why a Queue Item is not delivered to the end user.
In case you haven't received your message, check the following cases.
If it's Pending, you might want to check
If it's Failed, open your Queue Item Details and check the Result field
If it's Complete, keep reading
Most of the messaging providers are using APIs to handle an internal queue for the messages. This means that a provider might receive an item from e-satisfaction but stuck in their queue.
This will result in seeing a Complete status in e-satisfaction queue but there might be an issue in the provider queue.
For email messages, you might wan to check your Junk/Spam folder in case the messages is there.
In general, you should check for user unsubscribe lists in case you have unsubscribed from the service sometime in the past and you are not receiving the message.