In a Microsoft Exchange Server 2016 or 2019 environment, a user creates a meeting request in Outlook or Outlook on the web client and sets the Reminder to "None". When the attendee receives the meeting request, the reminder is changed to "15 minutes". It's expected that the reminder is set to "None".
In addition, you try the following steps to fix this issue, but the meeting reminder is still set to "15 minutes" when the attendee receives the meeting request:
Put a file that's named StoreDriver.config into Exchange installation Bin folder, such as C:\Program Files\Microsoft\Exchange Server\V15\Bin with the following contents:
<?xml version="1.0" encoding="utf-8" ?>
<add key="AlwaysSetReminderOnAppointment" value="false" />
Restart the MSExchangeDelivery service.
Create a meeting request and test again.
This issue occurs because the Exchange server doesn't load the XSD to validate the XML of StoreDriver configuration file. This ultimately causes the Exchange server not to consume StoreDriver.config.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
Learn about the terminology that Microsoft uses to describe software updates.