Error 550 5.7.1 RESOLVER.RST .AuthREquired; authentication required
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Error 550 5.7.1 RESOLVER.RST .AuthREquired; authentication required

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Article ID: 154357

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Updated On:

Products

Messaging Gateway

Issue/Introduction

 When a Microsoft Exchange server version 2010 is used as a downstream server where the SMG is configured with the following configuration, the sender may receive an non-deliry report (NDR, also known as the 'undeliverable e-mail') back after sending an e-mail to a distribution list that contains only a single user, where the sender is outside of the organization and is not a part of the Active Directory domain that the Exchange server is a part of.  These NDRs have a copy of the message as well as the error with the error code of "550" mentioned below.

 Error 550 5.7.1 RESOLVER.RST .AuthRequired; authentication required

Resolution

The "Preserve recipient addresses" setting needs to be disabled by unchecking that configuration option and saving the change.  This will allow for e-mails to be delivered successfully.


Applies To

 Configuration that will trigger the above error:

  • Microsoft Exchange version 2010 distribution list (DL) group: contains a single (i.e. only one) domain user account.
  • The DL group has the "Require that all senders are authenticated" setting enabled, under the "Message Delivery Restriction" configuration section on the Exchange server.
  • SMG configuration: "Preserve recipient addresses" is enabled (under Administration->Settings->Directory Integration, the "Directory Integration Settings" page, inside the "Address Resolution Options" configuration section.
  • Emails are originated from outside of the domain (external senders).
  • Destination e-mail address is the DL list and not the individual user, for example: [email protected].