Fixing the Outlook Address Cache / Autofill after recreating email address in Exchange

Recently I had a scenario where we wanted to convert a distribution group to a user mailbox. This was an email address that everyone uses. Of course this can't be done without deleting the dist group and creating as a user mailbox. Unfortunately when you delete the distribution group and recreate as a user the Outlook autocomplete / autofill will break because the value that outlook looks at is different for the new object.

This will result in a NDR like the following: (for dist group test@mydomain.org)

Delivery has failed to these recipients or groups:

'Test' <mailto:IMCEAEX-_O%3DHERE_OU%3DEXCHANGE%2B20ADMINISTRATIVE%2B20GROUP%2B20%2B28FYDIBOHF23SPDLT%2B29_CN%3DRECIPIENTS_CN%3DTesta56@mydomain.com>

The e-mail address you entered couldn't be found. Please check the recipient's e-mail address and try to resend the message. If the problem continues, please contact your helpdesk.

Diagnostic information for administrators:

Generating server: Server.mydomain.com
IMCEAEX-_O=HERE_OU=EXCHANGE+20ADMINISTRATIVE+20GROUP+20+28FYDIBOHF23SPDLT+29_CN=RECIPIENTS_CN=Testa56@mydomain.com
#550 5.1.1 RESOLVER.ADR.ExRecipNotFound; not found ##



As Ben points out this can easily be fixed: https://www.simple-talk.com/sysadmin/exchange/exchange-e-mail-addresses-and-the-outlook-address-cache/

This helps keep our 200+ users from having to fix on their own or more likely calling the help desk to have us fix it


And to help convert the IMCEAEX string
http://support.microsoft.com/kb/2807779