WP Better Emails plugin adds a customizable good looking HTML template to all WordPress default plain/text emails and lets you set a custom sender name and email address.
All emails from WordPress (lost password, notifications, etc.) are sent by default in text/plain format. WP Better Emails wraps them with a much better looking customizable HTML template and lets you also set your own sender name and email address.
WP Better Emails comes with a default simple and clean template that has been tested on various and popular email clients like Gmail, Yahoo Mail, Hotmail/Live, AOL, Outlook, Apple Mail and many more. This to ensure your emails will always display nicely in your recipient mailbox. But you can of course design your own.
WP Better Emails lets you send sample emails to test and preview your own custom template.
All emails sent by this plugin are as ‘multipart’ so email clients that don’t support HTML can read them.
Download and info: http://wordpress.org/extend/plugins/wp-better-emails/