Moving from on-premise to Exchange online, should I keep using Public Folder for Address Book?

Hello JaxPlanet,

You have many ways to achieve your goal.

You could create a custom address list for those contacts: https://learn.microsoft.com/en-us/exchange/address-books/address-lists/address-lists

You could use a shared mailbox with a security group: https://learn.microsoft.com/en-us/outlook/troubleshoot/calendaring/how-to-share-calendar-and-contacts

You can migrate your public folders to O365 groups, ( usually recommended but for this specific scenario may not be the best solution 😞 https://learn.microsoft.com/en-us/exchange/collaboration-exo/public-folders/migrate-your-public-folders-to-microsoft-365-groups

From my perspective, only for contacts, option 1 or 2 will be OK for you. And finally, of course, you can still use PF in exchange online, even if it's not the recomended way to go 🙂

Hope this helps and wish you a good day.