There are two unknown user action options affected by this, Transfer to Account, and Redirect to server. Both of these options cause mail accepted onto the server to increment the licensed user count.
This count was introduced to prevent unlicensed usage of the GMS Anti-Virus and GMS Anti-Spam modules. With Build 3539 the count was incremented for all incoming mail on all GMS installations.
Builds later than 3539 only increment the count in this way for systems that are actually running the GMS Anti-Virus and GMS Anti-Spam modules. Additionally the Transfer to account option only increments the count if the transfer is to an external address.
A short term workaround for this issue is to use the Fail to Account unknown user action. As this is not actually accepting the full message into the server, it does not increment the licensed user count.
Keywords:Unknown user action licensed user count