Our custumer has some room list based distribution groups one has 124 room mailbox members.The Room Finder of Outlook (2010,2013,2016) is not able list or expand only this one distribution group with 124 room mailboxes other dls with less room mailboxes are working fine.The suggested times menu says when you choose this dl the "Suggestion are not provided because there are too many attendees". Did anyone met such type of issue? Is there any members limitation of room list distribution group from desktop Outlook client view? With OWA all dls are working without any problem. Our customer has Hybrid Exchange 2010 with Adfs and Adconnect.