Using Classic Outlook on Windows for personal email, calendar, and contact management
Dear EmsFQ,
Good day! Thank you for posting to Microsoft Community.
As per your description, l understand that your goal is to manage all the contact Items from a single account and share these contact items with the rest of the users in the same tenant. If so, it is currently available to share the contact folder with others, see **** Share a contacts folder with others - Microsoft Support **** for details.
You mentioned that the only problem with the previous setup is that end users cannot send an email to multiple contact groups from Address Book E and they can only email one at the time. As far as l know, we can send email to multiple contact groups from address book:
Based on my tests, we can type the name of contact group in the To field directly when create a new message. Outlook will show us potential matches from the address book. We can also click the To button to display the Select Names dialog. Type a few characters of the contact group name and click Go. Contact groups are shown in bold font. As shown in below screenshot, l can add three contact groups in the To field.
In the meantime, l am afraid that l cannot provide you a good suggestion as we forum team have limited test conditions for such case. If you need more suggestions, we sincerely recommend you contact our dedicated team: Outlook Management - Microsoft Q&A. You can discuss your case with qualified experts via this link and receive multiple perspectives. Experts there have comprehensive knowledge and experience with Outlook management. Hope you can continue to enjoy service there.
Thanks for your patience and cooperation.
Stay safe and health.
Sincerely,
Tammy | Microsoft Community Moderator.