Not a valid SMTP address when you migrate mailboxes to Exchange Online in a cutover migration

  • Article
  • Applies to:
    Exchange Online, Exchange Server 2016 Enterprise Edition, Exchange Server 2016 Standard Edition, Exchange Server 2013 Enterprise, Exchange Server 2013 Standard Edition, Exchange Server 2010 Enterprise, Exchange Server 2010 Standard

Original KB number:   2965789

Problem

You're performing a cutover migration to migrate all mailboxes from your on-premises Exchange organization to Exchange Online. The source server for the migration is running Microsoft Exchange Server 2016, Exchange Server 2013, Exchange Server 2010, or Exchange Server 2007. However, the migration attempt fails, and you receive the following error message:

"/o=NT5/ou=###xx##x#x##x###x##xxxx/cn=###xx##x#x##x###x##xxxx" is not a valid SMTP address"

Cause

This issue occurs if the migration batch includes invalid or stale global address list (GAL) entries.

Solution

To resolve this issue, follow these steps:

  1. Open Exchange Management Shell on the on-premises Exchange server.

  2. Run the following command:

    Update-GlobalAddressList -Identity "Default Global Address List" -DomainController "NameOfDomainController"

  3. Delete and then re-create the cutover migration batch in Exchange Online.

More information

Exchange Server 2003 uses the Recipient Update Service, and this creates and maintains Active Directory attribute values. This service is not included in Exchange 2007 and later versions. Therefore, stale or invalid entries can exist on objects in Active Directory Domain Services (AD DS) in Exchange Server 2016, Exchange Server 2013, Exchange Server 2010, and Exchange Server 2007. These entries don't present an issue until you try to migrate and create new cloud objects.

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