I just realized that I don't have a answer to this question, when I'm talking some friends we can't find the best simple solution to do this. Can I send a dynamically body, from a form with a prefixed subject? My question is about the most simple solution. []'s
You can launch the user's email program using a mailto link along with several paramaters:
mailto:[email protected]?subject=hi&body=hello,%20world!
However, a lot of people use webmail nowadays, for which it won't work - so the best option is to avoid using email. If you want feedback and don't want to host such a script on your own server, you can use a service such as PollDaddy or SurveyMonkey for this. If you want to encourage users to share a page with friends, ShareThis supports email.
You cannot do this in general without some server side help.
Plain html does not offer support for it.
Usually a link as proposed by Simon will do the trick, but this will not work for everyone.
Javascript and Java client scripting suffer from the "same origin" limitation, meaning that you have to deliver to the same server, unless the user jumps through hoops to allow the script to connect to other hosts.
There are many scripts available to do this.