some users mail boxes got migrated from USER@domainA.COM  to different doman i.e user@domain

that users (non migrated) are getting undeliverable message when they send to users both migrated & non migrated), Please see the error message .

As per the error message it is trying to find email address “” for users who are in @domainB.COM.

They are able to send email from their webmail . We tried outlook level troubleshooting like cleared autofill cache and pulled the recipient name from GAL, but no luck

is it something to do with LegacyDN attribute of contact object in domain A.COM?
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Derek SouterITO Svc Delivery Cons IIICommented:
you say that you tried clearing the autofill cache - and pulling from the GAL (the first two things I would try).  have you tried manually typing the new email address within Outlook?

as the email routing is working (you say that email from Webmail works), the issue would appear to be within Outlook.
pramod1Author Commented:
should I delete the nk2 file also
Derek SouterITO Svc Delivery Cons IIICommented:
the NK2 file is the autocomplete list (nickname file) - the autofill cache

try a simple test - start typing the name of a user that has been migrated, then delete it (press the delete key, or backspace - it should delete it from the cache)

then type the new email address in (or choose them from the GAL - assuming the GAL has been updated and shows the new email address)

if that works, then you just need to delete the old entries from all the NK2 files (there are ways to do that automatically for all users) - or give your users instructions on how to carry it out themselves

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today

From novice to tech pro — start learning today.