Dear AdvancedNetworkSolutions,
Good day! Thank you for posting to Microsoft Community. We are happy to help you.
Based on your description, I understand that you have a query "Outlook auto complete won't display 1 specific email/contact address". Before we proceed the investigation, we need more detailed information about the situation you are experiencing.
Please help us in isolating the issue by providing the following information:
- What version of Outlook are you using? See What version of Outlook do I have? (microsoft.com)
- Have you tried deleting the cache? Close Outlook and delete > %userprofile%AppData\Local\Microsoft\Outlook\RoamCache\Stream_Autocomplete_[Bunch of Numbers Here].dat or run the command Outlook /cleanautocompletecache to clean server-side copy of cache.
- Have you tried clearing the Autocomplete list? Go to File > Options > Mail > Send Messages > Empty Auto-Complete List.
We look forward to hearing from you, please let me know and provide a more detailed description so we can provide you with more specific assistance. Thank you for your cooperation.
Sincerely,
De Paul | Microsoft Community Moderator