function tell_friends() {
	var form = document.tfForm;
	
	if (form.tfSendName.value == '' || form.tfSendName.value.length == 0) {
		alert("Please input your name");
		return;
	}
	if (form.tfSendEmail.value == '' || form.tfSendEmail.value.length == 0) {
		alert("Please input your email");
		return;
	}
	if (echeck(form.tfSendEmail.value)==false) {
		alert("Please enter a valid email address in your email");
		return;
	}
	if ((form.tfReceiveName1.value == '' || form.tfReceiveName1.value.length == 0) &&
			(form.tfReceiveName2.value == '' || form.tfReceiveName2.value.length == 0) &&
			(form.tfReceiveName3.value == '' || form.tfReceiveName3.value.length == 0) &&
			(form.tfReceiveName4.value == '' || form.tfReceiveName4.value.length == 0) &&
			(form.tfReceiveName5.value == '' || form.tfReceiveName5.value.length == 0) &&
			(form.tfReceiveEmail1.value == '' || form.tfReceiveEmail1.value.length == 0) &&
			(form.tfReceiveEmail2.value == '' || form.tfReceiveEmail2.value.length == 0) &&
			(form.tfReceiveEmail3.value == '' || form.tfReceiveEmail3.value.length == 0) &&
			(form.tfReceiveEmail4.value == '' || form.tfReceiveEmail4.value.length == 0) &&
			(form.tfReceiveEmail5.value == '' || form.tfReceiveEmail5.value.length == 0)) {
		alert("Please input your friends' name and email");
		return;
	}
	if ((form.tfReceiveName1.value != '' && form.tfReceiveName1.value.length > 0) &&
			(form.tfReceiveEmail1.value == '' || form.tfReceiveEmail1.value.length == 0)) {
		alert("Please input the email of friend 1");
		return;
	}
	if ((form.tfReceiveEmail1.value != '' && form.tfReceiveEmail1.value.length > 0) &&
			echeck(form.tfReceiveEmail1.value)==false) {
		alert("Please enter a valid email address of friend 1");
		return;
	}	
	if ((form.tfReceiveEmail1.value != '' && form.tfReceiveEmail1.value.length > 0) &&
			(form.tfReceiveName1.value == '' || form.tfReceiveName1.value.length == 0)) {
		alert("Please input the name of friend 1");
		return;
	}
	if ((form.tfReceiveName2.value != '' && form.tfReceiveName2.value.length > 0) &&
			(form.tfReceiveEmail2.value == '' || form.tfReceiveEmail2.value.length == 0)) {
		alert("Please input the email of friend 2");
		return;
	}
	if ((form.tfReceiveEmail2.value != '' && form.tfReceiveEmail2.value.length > 0) &&
			echeck(form.tfReceiveEmail2.value)==false) {
		alert("Please enter a valid email address of friend 2");
		return;
	}
	if ((form.tfReceiveEmail2.value != '' && form.tfReceiveEmail2.value.length > 0) &&
			(form.tfReceiveName2.value == '' || form.tfReceiveName2.value.length == 0)) {
		alert("Please input the name of friend 2");
		return;
	}
	if ((form.tfReceiveName3.value != '' && form.tfReceiveName3.value.length > 0) &&
			(form.tfReceiveEmail3.value == '' || form.tfReceiveEmail3.value.length == 0)) {
		alert("Please input the email of friend 3");
		return;
	}
	if ((form.tfReceiveEmail3.value != '' && form.tfReceiveEmail3.value.length > 0) &&
			echeck(form.tfReceiveEmail3.value)==false) {
		alert("Please enter a valid email address of friend 3");
		return;
	}
	if ((form.tfReceiveEmail3.value != '' && form.tfReceiveEmail3.value.length > 0) &&
			(form.tfReceiveName3.value == '' || form.tfReceiveName3.value.length == 0)) {
		alert("Please input the name of friend 3");
		return;
	}
	if ((form.tfReceiveName4.value != '' && form.tfReceiveName4.value.length > 0) &&
			(form.tfReceiveEmail4.value == '' || form.tfReceiveEmail4.value.length == 0)) {
		alert("Please input the email of friend 4");
		return;
	}
	if ((form.tfReceiveEmail4.value != '' && form.tfReceiveEmail4.value.length > 0) &&
			echeck(form.tfReceiveEmail4.value)==false) {
		alert("Please enter a valid email address of friend 4");
		return;
	}
	if ((form.tfReceiveEmail4.value != '' && form.tfReceiveEmail4.value.length > 0) &&
			(form.tfReceiveName4.value == '' || form.tfReceiveName4.value.length == 0)) {
		alert("Please input the name of friend 4");
		return;
	}
	if ((form.tfReceiveName5.value != '' && form.tfReceiveName5.value.length > 0) &&
			(form.tfReceiveEmail5.value == '' || form.tfReceiveEmail5.value.length == 0)) {
		alert("Please input the email of friend 5");
		return;
	}
	if ((form.tfReceiveEmail5.value != '' && form.tfReceiveEmail5.value.length > 0) &&
			echeck(form.tfReceiveEmail5.value)==false) {
		alert("Please enter a valid email address of friend 5");
		return;
	}	
	if ((form.tfReceiveEmail5.value != '' && form.tfReceiveEmail5.value.length > 0) &&
			(form.tfReceiveName5.value == '' || form.tfReceiveName5.value.length == 0)) {
		alert("Please input the name of friend 5");
		return;
	}
	if (form.message.value == '' || form.message.value.length == 0) {
		alert("Please input your message");
		return;
	}
	

	form.submit();
}