function checkemail(str){
    var testresults
    var filter=/^([\w-]+(?:\.[\w-]+)*)@((?:[\w-]+\.)*\w[\w-]{0,66})\.([a-z]{2,6}(?:\.[a-z]{2})?)$/i
    if (filter.test(str))
       testresults=true
    else{
        alert("Please input a valid email address!")
        testresults=false
    }
    return (testresults)
}