No, it works after I uncheck the 'authentication required' option. I'm just curious as to why it was being rejected in the first place considering the user WAS an authenticated user.

We had an internal email to a distribution list get rejected on our Exchange 2010 server with the error: 550 5.7.1 RESOLVER.RST.AuthRequired I've now gone in and changed this distribution list to allow unauthenticated users to send to it. However, in this particular case, the user was an internal, authenticated AD user. We had this happen one other time recently as well. Why would these be getting rejected?

Sorry...this is on an Exchange 2010 SP1 environment.

Dear have you tried this Remove the adpermission "ms-exch-smtp-accept-authoritative-domain-sender" from the NT Authority\Authenticated Users group by running the following cmdlet: remove-adpermission "connectorname" -user "Nt Authority\Authenticated Users" -extendedrights: ms-exch-smtp-accept-authoritative-domain-sender Regards

hi, >>>We had this happen one other time recently as well. you mean that e-mail is still rejected after you allow unauthenticated.My suggestion is: First you should increase diagnostic log level. Then new a group and test again.If still not work,we can find some useful information from these logs.And then fix your issue.Hope can help you. which log you should improve: MSExchangeTransport\SmtpReceive MSExchangeTransport\Routing MSExchangeTransport\Components MSExchangeTransport\Categorizer MSExchangeTransport\MessageSecurity MSExchangeTransport\Agents thanks, castin

Hi Cahrles You can also try this solution: Remove the adpermission "ms-exch-smtp-accept-authoritative-domain-sender" from the NT Authority\Authenticated Users group by running the following cmdlet: remove-adpermission "connectorname" -user "Nt Authority\Authenticated Users" -extendedrights: ms-exch-smtp-accept-authoritative-domain-sender Regards

Try below link http://social.technet.microsoft.com/Forums/en-US/exchangesvradmin/thread/b7128bf2-4ec0-4508-840f-32a34a12ac8b/ From the properties of the distribution list in Exchange Management Console: Mail-flow settings tab, Message Delivery Restrictions, un-tick Require that all senders are authenticated. Girishp

hi, any update? thanks, castin