In the current version of Exchange Online for Microsoft Office 365, you have to use the Windows PowerShell command line to create and configure shared mailboxes. Using PowerShell, you have to perform these steps:

Create a shared mailbox.

Configure the quotas for the new shared mailbox.

Assign the FullAccess permission so that security group members can open the shared mailbox.

Assign the SendAs permission so that security group members can send messages from the shared mailbox.

To make this task a lot easier, we created a GUI-based tool you can use to create and configure a shared mailbox, and then assign permissions to a security group so members can open the shared mailbox and send messages from it. It’s an easy, three-step process:

Download the Office 365 Shared Mailbox Tool.

Create a security group and add members.

Run the Office 365 Shared Mailbox Tool to create and configure a shared mailbox.

For more information about using shared mailboxes, see Set Up a Shared Mailbox.

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