function CheckData() {
    var retVals = false;
    var err = "";
    var temp = "";
    var haveName01, haveName02, haveName03, haveName04, haveName05, haveName;
    var haveEmail01, haveEmail02, haveEmail03, haveEmail04, haveEmail05, haveEmail;
    var errorEmail01, errorEmail02, errorEmail03, errorEmail04, errorEmail05, errorEmail;
    
    if (document.all) {
        var node_list = document.all.tags("input");
    }
    else {
        var node_list = document.getElementsByTagName("input");
    }
    
    for (var i = 0; i < node_list.length; i++) {
        var node = node_list[i];
        if (node.getAttribute('type') == 'text') {
            if(node.name.indexOf('txtName01') > -1) { if (!isNameEmpty(node.value)) haveName01 = true; }
            if(node.name.indexOf('txtName02') > -1) { if (!isNameEmpty(node.value)) haveName02 = true; }
            if(node.name.indexOf('txtName03') > -1) { if (!isNameEmpty(node.value)) haveName03 = true; }
            if(node.name.indexOf('txtName04') > -1) { if (!isNameEmpty(node.value)) haveName04 = true; }
            if(node.name.indexOf('txtName05') > -1) { if (!isNameEmpty(node.value)) haveName05 = true; }
            if(node.name.indexOf('txtFromName') > -1) { if (!isFromNameEmpty(node.value)) haveName = true; }
            if(node.name.indexOf('txtEmail01') > -1) {
                if (!isEmailEmpty(node.value)) haveEmail01 = true;
                if (!isEmail(node.value)) errorEmail01 = true;
            }
            if(node.name.indexOf('txtEmail02') > -1) {
                if (!isEmailEmpty(node.value)) haveEmail02 = true;
                if (!isEmail(node.value)) errorEmail02 = true;
            }
            if(node.name.indexOf('txtEmail03') > -1) {
                if (!isEmailEmpty(node.value)) haveEmail03 = true;
                if (!isEmail(node.value)) errorEmail03 = true;
            }
            if(node.name.indexOf('txtEmail04') > -1) {
                if (!isEmailEmpty(node.value)) haveEmail04 = true;
                if (!isEmail(node.value)) errorEmail04 = true;
            }
            if(node.name.indexOf('txtEmail05') > -1) {
                if (!isEmailEmpty(node.value)) haveEmail05 = true;
                if (!isEmail(node.value)) errorEmail05 = true;
            }
            if(node.name.indexOf('txtFromEmail') > -1) {
                if (!isEmailEmpty(node.value)) haveEmail = true;
                if (!isEmail(node.value)) errorEmail = true;
            }
        }
    }
    
    if (!haveName) { temp += "* Your name\n";}
    if (!haveEmail) { temp += "* E-mail\n";}
    if (!haveName01 && !haveName02 && !haveName03 && !haveName04 && !haveName05 && !haveEmail01 && !haveEmail02 && !haveEmail03 && !haveEmail04 && !haveEmail05) { temp += "* Name and E-mail receivers\n"; }
    if (temp != "" ){ err= "Please input required data for completion as follow(s);\n" + temp;}
    temp = "";
    if (haveEmail && errorEmail) { temp += "* Invalid email address\n"; }
    if (haveName01 || haveEmail01)
    {
        if (!haveName01) {temp += "* Name\n";}
        if (!haveEmail01) {temp += "* E-mail\n";}
        else if (errorEmail01) { temp += "* Invalid email address\n"; }
    }
    if (haveName02 || haveEmail02)
    {
        if (!haveName02) {temp += "* Name\n";}
        if (!haveEmail02) {temp += "* E-mail\n";}
        else if (errorEmail02) { temp += "* Invalid email address\n"; }
    }
    if (haveName03 || haveEmail03)
    {
        if (!haveName03) {temp += "* Name\n";}
        if (!haveEmail03) {temp += "* E-mail\n";}
        else if (errorEmail03) { temp += "* Invalid email address\n"; }
    }
    if (haveName04 || haveEmail04)
    {
        if (!haveName04) {temp += "* Name\n";}
        if (!haveEmail04) {temp += "* E-mail\n";}
        else if (errorEmail04) { temp += "* Invalid email address\n"; }
    }
    if (haveName05 || haveEmail05)
    {
        if (!haveName05) {temp += "* Name\n";}
        if (!haveEmail05) {temp += "* E-mail\n";}
        else if (errorEmail05) { temp += "* Invalid email address\n"; }
    }
    if (temp != "" ){ err += "Please verify the correctness of required data as follow(s);\n" + temp ;}
    if (err != "") {
        alert(err); retVals = false;
    }
    else
    {
        retVals = true;
    }
    return retVals;
}
function isNameEmpty(s)
{
    s = trim(s);
    if ((s == "") || (s == "Name")) return true;
    else return false;
}
function isFromNameEmpty(s)
{
    s = trim(s);
    if ((s == "") || (s == "Your name")) return true;
    else return false;
}
function isEmailEmpty(s)
{
    s = trim(s);
    if ((s == "") || (s == "E-mail")) return true;
    else return false;
} 
function trim(s)
{
	var l=0; var r=s.length -1;
	while(l < s.length && s[l] == ' ')
	{	l++; }
	while(r > l && s[r] == ' ')
	{	r-=1;	}
	return s.substring(l, r+1);
}