To send an email with updated fields only, use the following code in Edit page: Before record updated event.
var rmail = XVar.Array();
var body = new StringBuilder();
body.AppendLine("Changed fields");
foreach(var pair in values.GetEnumerator())
{
if (pair.Value != oldvalues[pair.Key])
body.AppendLine(String.Format("{0}: {1}", pair.Key, pair.Value));
}
rmail["to"] = "test@test.com";
rmail["subject"] = "Sample subject";
rmail["body"] = body.ToString();
MVCFunctions.runner_mail(rmail);
See also:
•Send an email to selected users