At the moment that is not possible but in the future versions we will make available MailBox resource for Exchange service plans which the customer will be able to buy from his control panel. You will be able to set a price for Mailbox resource and customer will be charged for each Mailbox resource he buys.

I would love to know a timeframe for this as all of our plans are based on single mailboxes and are not aggregated

I am pleased to announce availability of this most requested feature.

To create and sell exchange addons
Let's create an Exchange Mailbox addon with 3 price variations on volume discount principle:

(1) Exchange Mailboxes - $8.99/month
(3) Exchange Mailboxes - $22/month
(5) Exchange Mailboxes - $40/month

Go to Service Plans > Exchange Hosting Products > Edit

1. Click "Create Addon" button.
2. Select "System Managed" Addon.
3. Select "Mailboxes per Organization" from Select resource drop-down.
4. Type "Exchange Mailboxes" in addon display label field.
5. Select "Radio list" option from Addon display type drop-down.
6. Select "3" from How many options do you need drop-down and click Next.
7. In the Display name field enter "Exchange Mailboxes (3)" and in Internal value field enter "3". The value you enter in Internal value field should be numeric and this is used by the provisioning engine to determine additional mailbox units for the subscription. A value "3" means 3 additional mailbox unit. Click Next and then choose the billing cycle and set other criterias.

Now you have create Exchange mailbox addon and associated with a service plan. When this service plan is sold the client can shop for additional mailboxes from the Easy Shop menu in Customer Control Center.

I hope you like this 1st version of addon management and selling interfaces. Please give back your valuable suggestion to help us improve the software for you.

This feature will be available with next update. If you are licensed customer and cannot wait then please contact customer support for quick hotfix.