Common Fixes for Outlook on the Web (Exchange Online)

Troubleshooting Steps
Delivery has Failed to These Recipients or Groups
Too many recipients in Outlook

Sometimes, small issues can cause Outlook to throw an error. Please refer to this article for common fixes.

Troubleshooting Steps before Escalation:

  1. Try the Outlook Desktop App. If the desktop application works, you might be able to access what you need without troubleshooting.
  2. Try a different browser, clear browser cache or reset browser.
  3. Try building a new outlook profile. To do this, go to Control Panel > Mail > Profiles> Add Profile. Test out the new profile before deleting anything old. Note: rename the old .ost or create a new profile with a different name, this forces outlook to recreate the .ost.
  4. Run Office and system updates.
  5. Reboot your computer.
  6. Check your Network.
  7. Reach out to your Department IT or the service desk
  8. If none of the processes work, create a support ticket.

IMCEAEX or "Delivery has Failed to These Recipients or Groups" Errors:

This error is most often caused by the auto-complete field when trying to send a message. If you receive this error, try clearing your auto-complete field.

  1. Open a new message, start typing the name or address of the recipient.
  2. When the auto-complete suggestion appears, click the X next to the name to remove the suggestion.
  3. This deletes the cached address. Use To, to locate the correct address of the email if applicable.

Clear Suggestion in Outlook on the Web

  • Another issue could be that an email address has been changed or discontinued. Verify the email address includes a UNH affiliation:
  • If the email address has an old or out of date email address and you can’t contact them directly, try searching through the faculty/staff directory, or the Global Address List in Outlook Contacts.

Too many recipients in Outlook

The maximum number of recipients for an individual email through UNH IT mail servers is three hundred. If you try to send to more than 300 recipients in a single send, you will get an error similar to "This message wasn't delivered to anyone because there are too many recipients. The limit is 300."


Article ID: 1651
Fri 7/19/19 6:15 PM
Tue 11/16/21 3:23 PM
Applicable Institution(s):
Granite State College (GSC)
Keene State College (KSC)
Plymouth State University (PSU)
University of New Hampshire (UNH)
USNH System Office