var emailfilter=/^\w+[\+\.\w-]*@([\w-]+\.)*\w+[\w-]*\.([a-z]{2,4}|\d+)$/i
      function checkmail(e){
       var returnval=emailfilter.test(e.value) 
       return returnval
      }
     
      function email_doOnsubmit(theForm) {
                  if (theForm.vorname && theForm.vorname.value == "" ) {
                        alert("Please enter your first name!");
                        return false;
                    }

                    if (theForm.name && theForm.name.value == "" ) {
                        alert("Please enter your last name!");
                        return false;
                    }

                                       
                    
                   
                     if (theForm.email && theForm.email.value == "" ) {
                        alert("Please enter an e-mail address!");
                        return false;
                    }

                    if ( theForm.kommentar && theForm.kommentar.value == "" ) {
                        alert("Please enter a comment/message!");
                        return false;
                    }

                    if (checkmail(theForm.email) == false) {
                      alert("Please enter a valid email address.")
                      return false;
                    }
                   
                    theForm.referrer.value = document.location.href;

                    return true;
				}