Organizing and accessing contact information in Outlook.com
Hello James,
First, please try the method suggested in the AI-generated answer. If the usual correction does not work, try deleting the affected contact and creating it again with the correct email address. Before deleting it, copy any phone numbers or other details you want to keep.
Also search for the person’s name to check whether Outlook has saved more than one contact. An older duplicate may still contain the misspelled address, so remove or update any unnecessary copies.
For contacts synced from Gmail, iCloud, a phone, or another service, make the correction in the original service because it may overwrite changes made in Outlook during the next sync.
Please let me know how it goes after trying these steps, and I'll be glad to continue looking into it with you.