Delivery has failed and 550 5.1.1 RESOLVER.ADR.RecipNotFound NDR after a mailbox is moved to Microsoft 365

Original KB number:   2685437


The Hybrid Configuration wizard that's included in the Exchange Management Console in Exchange 2010 is no longer supported. Stop using the old Hybrid Configuration wizard and instead use the Microsoft 365 Hybrid Configuration wizard at For more information, see Microsoft 365 Hybrid Configuration wizard for Exchange 2010.


Assume that you have a hybrid deployment of on-premises Microsoft Exchange Server and Exchange Online in Microsoft 365. You use the Mailbox Replication Service through the Exchange Management Console or the Exchange Management Shell to move a mailbox from the on-premises environment to Microsoft 365. However, after the mailbox is moved, on-premises users and external users can't send mail to that mailbox in Microsoft 365. The sender receives the following non-delivery report (NDR):

Delivery has failed to these recipients or groups:

<Recipient email address>

Your e-mail was not delivered to all intended recipients. The e-mail address you specified doesn't exist, or may have been recently deleted. Please also check to ensure you typed the address properly. It is possible that your contact's e-mail address has changed and Outlook's AutoComplete has the old address stored. If this is the case, start typing their name in the To line, press the down arrow to select the outdated entry, and then press Delete. Now use the address book to locate the correct e-mail address.

Diagnostic information for administrators:

Generating server: <>

<Recipient email address>

#< # 5.1.1 smtp; 550 5.1.1 RESOLVER.ADR.RecipNotFound; not found> #SMTP#


This issue may occur if the on-premises mail-enabled user who represents the moved mailbox isn't stamped correctly with the target address. The Exchange server generates an NDR message because the on-premises Active Directory Domain Services (AD DS) can't locate the user in order to route the mail correctly.


To resolve this issue, add the target address, also known as the service routing address, to the mail-enabled user in the on-premises environment. To do this, use one of the following methods.

Method 1: Use the Exchange Management Console

  1. Open the Exchange Management Console on your local Exchange 2010 server.
  2. Select Microsoft Exchange On-Premises, and then select Recipients Configuration.
  3. Right-click the user, and then select Properties.
  4. On the E-mail Addresses tab, select Add, select SMTP Address, and then enter the email address. Use the <alias>@<domain> format for the email address.
  5. Select the name that you entered, and then select Set as Routing Address.
  6. Select OK.

Method 2: Use Exchange Admin Center

  1. In a web browser on your local Exchange 2013 server, browse to the Exchange Admin Center.
  2. Select Recipients, and then select Mailboxes.
  3. Select the user, and then select Edit.
  4. Select Email Address, and then select Add.
  5. Under Email Address, select SMTP, and then enter the email address. Use the <alias>@<domain> format for the email address.
  6. Select OK, and then select Save.

Method 3: Use Active Directory Service Interfaces Editor (ADSI Edit)


This procedure requires ADSI Edit. Using ADSI Edit incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems that result from the incorrect use of ADSI Edit can be resolved. Use ADSI Edit at your own risk.

  1. Select Start, select Run, type adsiedit.msc, and then select OK.

  2. Locate and right-click the user, and then select Properties.


    To determine the container to which the user belongs, view the user properties in the Exchange Management Console.

  3. Select the Attribute Editor tab, and then double-click Target Address.

  4. Type the external Simple Mail Transfer Protocol (SMTP) address.

  5. Select OK.

After the service routing domain is set up, confirm that the issue is resolved.

More information

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