I am Dale Hayter, a Microsoft and VMware certified Technical Consultant.

My blog has been built up over the years from my experience of working on an IT helpdesk and also from being out on-site.

Meeting invitations received from external domains show as regular email messages on the BlackBerry smartphone

By default, ProcessExternalMeetingMessages is set to False on Microsoft Exchange Server 2010. The correct setting for BlackBerry Enterprise Server is True

Run this powershell to resolve the issue.

Get-Mailbox -Server "servername" -ResultSize Unlimited -Filter {RecipientTypeDetails -eq 'UserMailbox'} | Set-CalendarProcessing -ProcessExternalMeetingMessages $true