SearchableMailbox.IsExternalMailbox property

Gets or sets a value that indicates whether this is an external mailbox.

The IsExternalMailbox property is applicable for clients that target Exchange Online and versions of Exchange starting with Exchange Server 2013.

Namespace:  Microsoft.Exchange.WebServices.Data
Assembly:  Microsoft.Exchange.WebServices (in Microsoft.Exchange.WebServices.dll)

public bool IsExternalMailbox { get; set; }

Property value

Type: System.Boolean
true if an external mailbox; otherwise false.