Back in 2017, we announced SharePoint site mailboxes in Microsoft 365 were being deprecated, and that new organizations would no longer have access to the feature and existing organizations would no longer be able to create site mailboxes. Since that announcement, we have seen site mailbox usage drop consistently as customers move to alternative solutions. There are still a few customers who have site mailboxes with some activity, as well as customers who want to archive and delete site mailboxes that are no longer in use.
As an alternative to site mailboxes, we had previously recommended Microsoft 365 Groups (formerly Office 365 Groups) and today, when you create a team site in SharePoint, a Microsoft 365 Group is created automatically. You can also connect classic team sites to a new Microsoft 365 Groups group. This gives you a shared inbox all team members can leverage among the other group apps. It will also modernize your classic site.
Before we retire (and ultimately delete) all SharePoint site mailboxes from Microsoft 365 (April 2021), we’ll publish another update as a reminder. In the meantime, you can back up the data in your existing site mailboxes using this instruction guide.