Sure you can! The 'message' field for the email is just the same as a calculation field. You can use the same notation and references to a field or a function. You can type this in the field to get you example:
"Hello Richard¶¶" & "This is a text List¶¶" & "Product: " & Product::Name & "¶" & "Customer: " & Lookup(Product Customer::Name; "Not Found") & "¶¶" & "Greetings¶" & "Tony" I hope this will help you, despite this being a old question.
See the docs: http://www.filemaker.com/help/13/fmp/en/html/scripts_ref2.37.70.html#1029660