Campaign Monitor is a pay-as-you-go email marketing tool with a feature to allow web designers (or WPMS admins) to resell/rebrand as their own product.
Admins can create sub-accounts for their clients/users, rebrand the interface, and set their own marked-up pricing to make a profit every time the clients/users send email newsletters or autoresponder sequences.
You can set up a CNAME so that the end-user never knows it's Campaign Monitor powering the email on the backend. They simply login to http://subdomain.your-wpmu-site.com.
An integration plugin to put in /mu-plugins/ that uses the Campaign Monitor API to automatically sync with the wp_users table.
1. Super-admin options page to input the main API key for the WP Network and set marked-up rates
2. New WPMS site owners (optionally) get a Campaign Monitor account created for them to do email marketing
3. Sidebar email subscribe widget
4. Dashboard widget for site admins to view their email subscribers (see example below)
5. Integration with MarketPress plugin - customers automatically added to email list (see example below)
Sample plugins to draw from:
Campaign Trail - lets you add a widget to your site that collects and saves email addresses to a database of Subscriber Lists that syncs seamlessly with your Campaign Monitor account. ** Integrates with the WP e-Commerce Plugin. **
WP Dashboard Plugin - This white label plugin pulls data from your Campaign Monitor lists’ feeds and displays them on your WordPress dashboard.