Convert a Mailbox to Shared Mailbox in Office 365

When you convert a user's mailbox to a shared mailbox, all of the existing email and calendar is retained but can be accessible to any users with delegated access to the mailbox.

Note: The user mailbox you're converting needs a license assigned to it before you convert it to a shared mailbox. Shared mailboxes can have up to 50GB of data without a license assigned to them.
  1. Open up a web browser to and login with your credentials.

  2. On the left side select the exchange admin center.

  3. Under recipients click mailboxes.

  4. Select the user that you would like to convert and on the right side click convert.

  5. Click shared to confirm that the mailbox is in the list of shared mailboxes.

  6. If the mailbox is smaller than 50 GB, you can remove the license and request that we lower your license count for billing.

Note: We recommend that you block sign in for the shared mailbox that you create to keep the account secure.