Exchange – Sending from Alternative Addresses in Exchange

quoted from: http://it.usu.edu/htm/faq/faq_q=1360

"The problem is the cached Outlook nicknames are remember the information from the old Active Directory (Blue). Even though a user types in a fully qualified email address like john.smith@usu.edu outlook remembers john.smith@usu.edu used to be mailto:IMCEAEX-_O=UTAH+20STATE+20UNIVERSITY_OU=FIRST+20ADMINISTRATIVE+20GROUP_CN=RECIPIENTS_CN=johsmi@mail.blue.usu.edu. Outlook tries to simply take the old username from the old domain and put that in the new domain. So it tries to send to mailto:IMCEAEX-_O=UTAH+20STATE+20UNIVERSITY_OU=FIRST+20ADMINISTRATIVE+20GROUP_CN=RECIPIENTS_CN=johsmi@aggies.usu.edu

Which makes the email bounce.

To resolve this issue:

We need to clear the Outlook nickname cache.

On XP/2000 the cache file is here:

C:\Documents and Settings\\Application Data\Microsoft\Outlook\.NK2

Close Outlook and delete the .NK2 file to get Outlook to forget previously entered information.

Under Vista it is here:

C:\Users\\AppData\Roaming\Microsoft\Outlook\.NK2

Close Outlook and delete the .NK2 file to get Outlook to forget previously entered information.

Deleting the .NK2 file only deletes the Outlook Cached addresses it does NOT delete the address book."

Hope this helps!

What you see are:

• Mailbox users (regular user symbol):
  • AD Users linked to a mailbox in your Exchange organization
• Mail-enabled users (user symbol with globe):
  • AD Users that have an email address, but no mailbox in your Exchange organization

This is commonly seen in organizations that have more than one email messaging platform deployed, ie. Exchange coexisting with a linux-based mail platform sharing the same recipient domain/namespace.