One person I email daily does not appear in TO field quick list.

Hi chuckmi,

to troubleshoot your issue, you can try this:

1. Verify Auto-Complete Settings in Outlook:

   • Open Outlook.
   • Navigate to File > Options.
   • Select the Mail tab.
   • Ensure that the option "Use Auto-Complete List to suggest names when typing in the To, CC, and BCC lines" is checked.

2. Clear Auto-Complete List:

   • If the option is enabled, clear the Auto-Complete list.
   • Open Outlook.
   • Go to File > Options > Mail.
   • Under Send Messages, click "Empty Auto-Complete List".
   • Confirm by clicking Yes.
   • Test by sending emails to the same address to check if AutoComplete works.

If the issue persists, consider re-importing suggested contacts or deleting the AutoComplete cache.

Why are all my Outlook autocomplete email addresses suddenly missing? - Super User
Outlook auto complete won't display 1 specific email/contact address - Microsoft Community