ADManager Plus allows you to create Shared Mailboxes in both the on-premise Exchange Server as well as the on-demand Office 365 environments, simultaneously, from a single web-based console. You can also create Shared Mailboxes in just Office 365 or just Exchange, as per your requirement.
To create a new Shared Mailbox,
Click the Management tab.
Select Mailbox Management from the options on the left hand side.
Click the create single shared mailbox link.
The create single shared mailbox page will open up. Check/uncheck the checkboxes for Active Directory and Office 365, depending on where you want to create the shared mailbox. Select the domain in which you wish to create a new shared mailbox.
Select the mailbox creation template that you wish to use to create the shared mailbox. If you do not specify any template, the default template specified by the administrator will be used.
Click the General tab
Enter the appropriate values for all the fields. Display Name, E-mail and Container are mandatory attributes for creating a shared mailbox. All mandatory attributes will be highlighted in red.
Click the Contact tab and enter relevant values for all the telephone, organization and address fields.
Select the Exchange Tab and enter relevant values for all the fields. You must specify values for the Mailbox server, mailbox store and mail alias attributes which are mandatory for creating a shared mailbox.
In the Delegation tab, select the desired users for the send on behalf, send as and full access rights for this shared mailbox
In the Custom attributes tab, select the custom attributes ( configured in the schema) that you wish to add in ADManager Plus. To add a custom attribute permanently in the tool, click the configure custom attribute link; use the add additional attribute link to add a custom attribute for only a specific operation.
If you want to create shared mailbox in Office 365, click the Office 365 tab. Select the appropriate option from the ones listed to specify whether the DirSync option has to be enabled or disabled during mailbox creation.
Click the Create button to create the new shared mailbox.