Answer:
Application Layer
Explanation:
According to my research on information technology and networking, I can say that based on the information provided within the question the problem is most likely residing in the Application Layer. This is the layer that contains the communications protocols and interface methods. It can also be said that the problem most likely resides in this layer because the users can still retrieve their emails which means that the servers are still up and running, therefore it is an application layer problem.
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