function checkEmail(a_mail) 
{
	mymail 				= a_mail;
	var mail_err 	= 0
	var r_mail 		=  /^([a-z0-9]+([a-z0-9-_]+)*\.)*[a-z0-9]+([-_]?[a-z0-9]+)*@([a-z0-9]+([-_]?[a-z0-9]+)*\.)+[a-z]{2,4}$/
	ok_mail 			= r_mail.exec(mymail);
	
	if (!ok_mail) 
	{
		return false;
	} 
	else 
	{
		return true;
	}
}