The WordPress Campaign Monitor Plugin is an email newsletter / SMS tool built for WordPress. Users can send campaigns, track the results and manage their subscribers.
Sending emails has been modified and now works on WAMP WIMP LAMP WinApache, WinIIS, LinuxApache servers.
Some core features
» Complies with NZ & USA CAN SPAM ACT
» Comes with its own WordPress Widget
» Integrates with the WordPress e-Commerce plugin
If you want to integrate an HTML template with your campaign then you will have to contact Instinct directly.
Update: Tested with WordPress 2.5