Normally you can. Simply use the concatenation function '&' in excel. For example:

=(Hyperlink("Mailto:me@home.com?Subject=" & A3 & "&Body=" & A2 & "Kind
+ regards"))
[download]

This will put the content of cell A3 in the subject and A2 into the body.

Search in google on: 'excel mailto body' for other examples.

Kind Regards

Martell