The "Exchange Server Toolbox" considers all user mailboxes on the exchange server but without room and device mailboxes.
In the configuration interface under Licensing you can see which and how many mailboxes the "Exchange Server Toolbox" uses for licensing.

There you can also exclude individual mailboxes from processing and thus from licensing.

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In this case the "Exchange Server Toolbox" will start sending notification mail to administrator accounts and after some time it will stop processing rules including anti-spam and anti-virus rules.

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The number of mailboxes available AND installations per Exchange Server are depending on your "Exchange Server Toolbox" license.
There are licenses that reach from up to 10 mailboxes up to an unlimited amount of mailboxes.
For more information on different "Exchange Server Toolbox" Editions and license offers refer to:
https://www.jam-software.com/exchange_server_toolbox/prices.shtml

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There are 3 possible reasons why "Demo version" still shows up:
1. You did not download and install the full version from the URL you received after the purchase.
2. You have accidentally installed the trial version again. (Have you been asked for a installation key?)
3. You have installed the full version to a different folder than the trial version, which is now still on your disk.

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The "Exchange Server Toolbox" uses .Net regular expressions with the options IgnoreCase and Singleline set to true.

A tool for testing .NET regular expressions can be found here:
https://regex101.com/

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