Hello, I am dealing w/ an issue were messages are being returned when some of my users attempt to send an email to a recipient in the same organization. I don't see any issues with the recipients mailbox configuration. The exact error in the NDR is: IMCEAEX-_O=U+26H_OU=US_cn=Recipients_cn=alias@domain.com #550 5.1.1 RESOLVER.ADR.ExRecipNotFound; not found ## The NDR is being generated by my cas/hub server. Any insight would be greatly appreciated.

Probably a cached entry in Outlook. Have them pick the user explicitly from the GAL, or simply delete the cached entry for the user in Outlook when it autofills ( highlight - hit delete) Alternatively, create a x500 custom proxy address based on that old legacyExchangeDN and add it to the recpient's account.

thanks for the response. ive been just deleting the cached address but the issue keeps reappearing. ill give the second option a go and see if that works. thanks again i really appreciate it. ill report back after making the change .

where can i pull the legacyExchangeDN ??

Hi, Get the LegacyExchangeDN of the mailbox using following Powershell command in EMS: get-mailbox user@domain.com |FL LegacyExchangeDN Now match this DN with the DN shown in the NDR IMCEAEX-_O=U+26H_OU=US_cn=Recipients_cn=alias@domain.com Only the end value "CN=something" would be different. Now add the old LegacyDN to your your users email addresses as X.500 email address. Regards, Laeeq Qazi|Team Lead(Exchange + Sharepoint + BES + DynamicsCRM) www.HostingController.com

where can i pull the legacyExchangeDN ?? Hi, This is a must see article regarding the issue u r facing. http://www.simple-talk.com/sysadmin/exchange/exchange-e-mail-addresses-and-the-outlook-address-cache/ It contains a powershell way to add an X.500 email address to the mailbox. Regards,Laeeq Qazi|Team Lead(Exchange + Sharepoint + BES + DynamicsCRM) www.HostingController.com

thanks all for the responses, you saved my butt on this one !! laeeq that article was extremely helpful. i was able to find the legacy x.500 address by copying a user nk2 and then opening in an nk2 editor. seems to have been resolved !! thanks again !!