Yes, look all tips and tricks with mailto: http://www.angelfire.com/dc/html-webmaster/mailto.htm
mailto subject example:
<a href="https://stackoverflow.com/questions/4782068/mailto:no-one@snai1mai1.com?subject=free chocolate">example</a>mailto with content:
<a href="mailto:no-one@snai1mai1.com?subject=look at this website&body=Hi,I found this website and thought you might like it http://www.geocities.com/wowhtml/">tell a friend</a>As alluded to in the comments, both subject and body must be escaped properly. Use encodeURIComponent(subject) on each, rather than hand-coding for specific cases.
As Hoody mentioned in the comments, you can add line breaks by adding the following encoded sequence in the string:
%0D%0A // one line break