You will need to install Valentina Server and Valentina Studio. Both apps need to have the same version as the Valentina version that is used by Mail Archiver X Pro. For Mail Archiver 5 this is Valentina version 8.7. You will NOT have to pay for anything in the Valentina Store.
You need to download and install Valentina Server from the Valentina website
Double-click the pkg file.
And follow the instructions of the installer:
The server is located at Library/VServer_x64. There are 2 important subfolders. The license folder contains the necessary licenses to run Mail Archiver X Pro. In the databases folder the archive of Mail Archiver will be located. You can't start the server without a license. A free license for evaluation purposes is available at the Valentina store. In the confirmation mail is a license file. Copy this file to the licenses folder.
When you buy a license for Mail Archiver X Pro, then you will get a license for Valentina-Server for the production environment.
Open the System Preferences and select "Valentina Server". Click on the button showing "Start" so that it changes to "Stop".
Valentina Studio is necessary for server and user maintenance. It can be downloaded either from the Valentina website or from the Mac App Store. The version from the Valentina website needs to be registered, but it is free, too.
The Valentina Studio version from the Mac App Store obviously doesn't need to be installed. The version from the Valentina website has a simple dmg, where the application just has to be dragged to the applications folder.
Use the Installer application to install the main application. The application is started when the installer finishes. Before being able to connect you have to do one final step. Go to applications/Mail Archiver X Pro/Extras and start the application "Index Helper". This needs to be done only on the machine that is running the server. You can use Mail Archiver X Pro without this helper application. But then searching for content in the message body will be slower.
Click on the Select button to select a location of the index. The default location is the Documents folder. Then click the Start button. The Status should say "Server is running". That is all that you have to do.
If you have an existing archive that you want to use with the server version copy the file to /Library/VServer_x64/databases. That's not the user library folder!
Now go back to Mail Archiver. Open Setup from the toolbar and go to Data Format. Then enter Server, Database, User Name and Password. There is a default user with username "sa" and password "sa". You can use this for testing. Click on the Connect button. In the Index Helper you should see that a database has connected. In the lower area you should see that the main app is talking to the Index Helper.
Because the archive doesn't exist and the user is an administrator he/she is asked if the archive should be created:
If the entered information is correct then the archive is created and opened in the background. You can close the Setup.
If you already have an archive and only want to use the database in the server then you can copy the existing archive into Library/VServer64/databases. This is neither the System/Library nor the user/Library folder!
Mail Archiver will only "see" the database if you register the database in Valentina Studio. Open Valentina Studio and connect to the server (here localhost). You should see the database that you just copied but with a yellow asterisk. Do a right mouse-click on the database and select "Register Database". The yellow asterisk will vanish and you can now use the database from Mail Archiver.