In the latest release of PSA (3.10.30.41), when you try to import Exchange Appointments for a week that has at least one appointment/meeting with a mention in it, the import process fails with the following error:

"Could not retrieve appointments because: The property Mentions is valid only for Exchange Exchange2015 or later versions."

It would be brilliant if the current import process were updated to support mentions and other Exchange properties that have a version higher than Exchange 2015.