Your email program is using outdated address information .....

Tags Oak


Email bounced back, message indicates address book is outdated.

Your message to couldn't be delivered.

Your email program is using outdated address information for


Office 365

IMCEAEX-_o=NT5_ou=00. . .

Action Required








Outdated To address



How to Fix It

To stop your email program from using outdated address information, clear the recipient Auto-Complete List in Outlook or Outlook on the web by following the steps in this article, or by doing the following:

  • Identify the recipient who didn't receive your message by looking at the To or CC information located in the Original Message Headers section below. Recipients whose names are followed by a set of characters that start with 'IMCEAEX' or 'imceaex' didn't receive your message.
  • Click New mail (in Outlook) or New Email (in Outlook on the web).
  • In the To box, start typing the recipient's name or email address until the recipient's name appears in the drop-down list.
  • Use the Down Arrow and Up Arrow keys to select the recipient, and then press the Delete key to delete the Auto-Complete List entry.
  • In the To box retype the recipient's email address and then resend the message.

If the problem continues, forward this message to your email admin. If you're an email admin, refer to the More Info for Email Admins section below.


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This article applies to 


Email address was selected from the Dartmouth Offline Address book (default), offline address book appears to be out of date.  The Global address book has an entry for the email recipient and it was used to resend the email without issue.





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Article ID: 83808
Thu 7/25/19 4:00 PM
Fri 3/17/23 10:55 AM