internal mailbox always cannot receipt email with error:LED=550 5.1.11 RESOLVER.ADR.ExRecipNotFound; Recipient not found by Exchange Legacy encapsulated email address lookup

Question

After upgrade to exchange 2016 from 2013, someone cannot receipt email, and I checked the email failed to sent with below error information.

---

This recipient wasn't found at the email address you specified. Please check the address.

[{LED=550 5.1.11 RESOLVER.ADR.ExRecipNotFound; Recipient not found by Exchange Legacy encapsulated email address lookup};{MSG=};{FQDN=};{IP=};{LRT=}]

---

but I found the problem only happen in who always send email to by outlook. as I never to send email to issue mailbox, so when I send email to issue mailbox, that is success, and it also success with external and OWA.

I refered some similar case and follow it to add X500, seems it has not work for my case.

https://learn.microsoft.com/en-us/answers/questions/1375844/remote-server-returned-550-5-1-11-resolver-adr-exr

Answer 1

Hi,alan99

Welcome to the Microsoft forum.

Based on your description, it may be because the recipient's mailbox was moved or changed in some way during the upgrade process, and it is specific to users who use outlook and have sent it mails before, and it may be related to the cached autocomplete list, which can be cleared for all users who are unable to send mails to it: File->Option->Mail->Empty Auto- Complete List

Also,I recommend you to download the address book : Send/Receive-> Send/Receive Group->Download Address Book

 

I hope this helps.Please feel free to contact me for any updates.