How to enable Exchange for hosted SharePoint accounts through Apps4Rent Control Panel:

1. Login into the control panel and click on Advanced Administration.
2. Click on Company Info.
3. Put a Check mark next to Enable Exchange and Enter the new domain and click on on Add Domain.

You need to put some domain even if you want to use Exchange with your Primary Domain. Later you can remove the domain.

4. Scroll to the bottom and click on Update button.
5. Click on Update. Now, you need to add users who would be using the Exchange mailboxes.

Related Links :

MOSS 2007

Hosted Apps – Exchange SharePoint

Hosted Exchange SharePoint Services

Free WSS 3.0 Hosting Application Templates

Changing Exchange mailbox sizes

Add new SharePoint site with new domain