Note NDRs can occur for various reasons. However, the resolution that is mentioned in the "Resolution" section is specific to the causes that are mentioned in the "Cause" section.
When you use an at sign (@) in the name of a source environment contact, and when that name is synchronized with the managed environment if the following conditions are true, you receive the NDR that is mentioned in the "Symptoms" section:
The contact is set to be hidden from the global address list (GAL) in Microsoft Exchange.
The contact object is for a non-company (external) contact. For example, the contact object is for a user who is not part of your company.
Mail is received by the Exchange 2010 managed environment through a receive connector that is set to be Externally Authoritative in Exchange PowerShell or to be Externally Secured in Exchange Console.
Mail is replied to on a BlackBerry device.
To resolve this issue, follow these steps:
Delete the contact in the source Active Directory schema.
Let two Microsoft Managed Services Service Provisioning Provider (MMSSPP) synchronization cycles finish. This makes sure that the contact is removed from the managed environment.
Re-create the contact in the source Active Directory schema without using the at sign (@) in the name or display name when you create a contact that will be synchronized with the managed environment.
You must not use the at sign (@) in the name or display name when you create contacts in Active Directory that will be synchronized with the managed environment.
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