Using Classic Outlook on Windows for personal email, calendar, and contact management
Dear Brittany S.,
Thanks for your reply!
For this issue, I used my Microsoft 365 for business account to do some test, when sharing the contacts, since it's a folder accessing/editing permission shared to another user, the other use will have permission to use the contacts. But for the autocomplete/suggested contacts feature, the contact will not be added into the list automatically, it's a design limitation.
I did some research on the autocomplete/suggested contacts and would like to share some information about it:
These suggestions are broken into two categories:Recent PeopleandOther Suggestions*. The names and addresses that appear inRecent Peopleare stored in theAuto-Complete List. The names and addresses that appear inOther Suggestionsare generated within the Microsoft 365 Service using information indexed from the sender’s previous communications.*
More information please refer to the document: Manage suggested recipients in the To, Cc, and Bcc boxes with Auto-Complete - Microsoft Support
We can see that if you need the shared contacts be added into autocomplete/suggested contacts, you might need to send some emails to these contacts, then wait for some period, the contacts would be auto populating when you send emails in the future.
I hope the information can be useful. If there is any update or I misunderstand you, please feel free to let me know. I will continue to assist you. Your understanding and co-operation are highly appreciated.
Thanks for your precious time. Have a nice day!
Sincerely,
Sherry | Microsoft Community Moderator