Well, there are actually 2 ways to do that.
- The first “way” is a workaround. As adviced by Microsoft, use the regarding field for your attendees, and simply stop using the (required and optional) attendees fields. This is of course not always acceptable.
- The serious way: create an Exchange transport (mail flow) rule. This rule can be designed as follows. For messages where:
- The recipient is located Outside the organization (ToUserScope = NotInOrganization )
- The message type is Calendaring (MessageType = Calendaring)
- The subject contains “DONOTSENDINVITE” (for example)
- => Delete the message
Such a rule is quite easy to create and to manage. Of course, you then create a dependency on Exchange, but it’s quite effective.
The fact is that Exchange actually sends the invites by default, so we need a way to stop that. And the Exchange rules do not cover many fields that are common to both Echange and CRM.