On Outlook on the web/Outlook.com, suggested recipients in the To/Cc/Bcc boxes are managed directly from the suggestion list rather than from a central “AutoComplete list” settings page.
To manage or hide individual suggested recipients:
- Start a new message (or reply/forward).
- In the To, Cc, or Bcc box, start typing the name or email address.
- When the unwanted suggestion appears, look for an X to the right of the name.
- Select the X to remove/hide that suggestion.
- After this, that contact will no longer be returned as a suggested contact in Microsoft 365 products (for example, Outlook, Teams).
- To unhide a contact later, send an email to that address (by replying to an old message or typing the full address). After about 24 hours, it will start appearing again in suggestions.
If the X is not visible, the current Outlook on the web UI being used may not support bulk or central management of the suggestion list beyond this in-line removal behavior. There is no documented method in the provided material to clear all web-based suggestions at once from Outlook on the web/Outlook.com.
References:
- Manage suggested recipients in the To, Cc, and Bcc boxes with Auto-Complete in Outlook for Mac
- The Outlook AutoComplete list
- Outlook replies or forwards cause non-delivery error “Your message did not reach some or all of the intended recipients”
- Create, edit, or delete a contact list (or contact group) in Outlook