Your message to IMCEAE[email protected]usprd01.prod.outlook.com couldn’t be delivered.
Your email program is using outdated address information for IMCEAE[email protected]usprd01.prod.outlook.com.
More Info for Email Admins
Status code: 550 5.1.11
The recipient email address is a LegacyExchangeDN address, which isn’t used by the Office 365 service. You might see this error if you’ve migrated your organization’s email from on-premises to the cloud, or if your organization has a hybrid configuration and you synchronize your on-premises directory with Office 365. If clearing the recipient Auto-Complete List from the user’s Outlook or Outlook on the web doesn’t solve the problem, try to clear the related LegacyExchangeDN address from your on-premises Active Directory. Then synchronize the directory again.
For more information, see Fix email delivery issues for error code 5.1.11 in Office 365.
Outdated To address
Most of the time, as described in the Error message, all we need to do is to remove the address from auto complete list/cache, then type the full address manually. Here’s the steps
1 Create a new email in Outlook
2 Type the beginning of the recipient email address
3 Click on the “X” to remove it from the cache/auto complete list in Outlook
4 Type the full recipient email address manually.
Try to send again, this time, the email should reach recipient’s inbox successfully.