Summary:

The Spam Analysis Queue holds messages that are to be processed by the EMF Anti-spam engine. After messages are processed by the Anti-spam engine, they are placed into the Inbound queue for processing by the Policy Engine.

Resolution:

Running the following query in SQL Query Analyzer will tell you how many messages are currently in the Spam Analysis Queue:

USE EMFMail
SELECT COUNT(*)
FROM RelayStoreMessageHeaders WITH (NOLOCK)
WHERE queueName = 'spam'

Additional Info:

In EMF 5.6 and later, the Spam Analysis Queue has been exposed in the Web Admin under the Status page.