function valida_envia(){ 
   	
   	//First name 
   	if (document.contactreservation.FirstName.value.length==0){ 
      	 alert("Por favor, escribe tu nombre") 
      	 document.contactreservation.FirstName.focus() 
      	 return false; 
   	} 
	
   //Phone number 
   	 if ( isNaN( document.contactreservation.Phone.value) ) {   
        alert("Por favor, escribe un número de teléfono valido")  
        document.contactreservation.Phone.focus() 
        return false; 
   }
   
    //comentarios 
   	if (document.contactreservation.comments.value.length==0){ 
      	 alert("Por favor, escribe un comentario") 
      	 document.contactreservation.comments.focus() 
      	 return false; 
   	}




   //Email 
   	if (document.contactreservation.Email.value.length==0){ 
      	 alert("Por favor, escribe tu Email") 
      	 document.contactreservation.Email.focus() 
      	 return false; 
   	} if (!checkemail( document.contactreservation.Email.value)) {   
        alert("Por favor, escribe un Email valido")  
         document.contactreservation.Email.focus() 
      	 return false; 

   } else if (!checkemail( document.contactreservation.Email)) {   
        alert+=("Por favor, escribe un Email valido")  
         document.contactreservation.Email.focus() 
      	 return false; 
   }
   
   

}


  function checkemail(str) {
		var at="@"
		var dot="."
		var lat=str.indexOf(at)
		var lstr=str.length
		var ldot=str.indexOf(dot)
		if (str.indexOf(at)==-1){
			return false;
		}
		if (str.indexOf(at)==-1 || str.indexOf(at)==0 || str.indexOf(at)==lstr){
			return false;
		}
		if (str.indexOf(dot)==-1 || str.indexOf(dot)==0 || str.indexOf(dot)==lstr){
			return false;
		}
		if (str.indexOf(at,(lat+1))!=-1){
			return false;
		}
		if (str.substring(lat-1,lat)==dot || str.substring(lat+1,lat+2)==dot){
			return false;
		}
		if (str.indexOf(dot,(lat+2))==-1){
			return false;
		}
		if (str.indexOf(" ")!=-1){
			return false;
		}
		return true;
	}