You could just use the php mail() function, which allows the user to write a message in the browser and send it from there, instead of firing up the email client.
If you really want an easy way to do this either Campaign Monitor or MailChimp is the way to go, they have very easy to use UI's and both offer a great email service.
Essentially what I need is a link that once clicked sends emails without opening outlook. If you could supply me with such a thing I'd be very happy.