function check_valid_form(Email1) {
	
	var invalidChars = " /:,;";
	
	if (document.forms["posters"].elements["Email1"].value == "") {
		alert("Please enter an email address");
		return(false);
	}
	
	for (var k=0; k<invalidChars.length; k++) {
				var badChar = invalidChars.charAt(k);
				if (document.forms["posters"].elements["Email1"].value.indexOf(badChar) > -1) {
				alert("Please check your email address");
				return false;
				}
			}
			var atPos = document.forms["posters"].elements["Email1"].value.indexOf("@",1);
			if (atPos == -1) {
				alert("Please check your email address");
				return false;
			}
			if (document.forms["posters"].elements["Email1"].value.indexOf("@",atPos+1) != -1) {
				alert("Please check your email address");
				return false;
			}
			var periodPos = document.forms["posters"].elements["Email1"].value.indexOf(".",atPos);
			if (periodPos == -1) {	
				alert("Please check your email address");
				return false;
			}
			if (periodPos+3 > document.forms["posters"].elements["Email1"].value.length)	{
				alert("Please check your email address");
				return false;
			}
	
	
	
	if (document.forms["posters"].elements["Email1"].value !=
		document.forms["posters"].elements["Email2"].value) {
		alert("The two e-mail addresses you entered were " +
			"different.\n" +
			"Please make them the same and then click " +
			'"Submit" again.');
		return(false);
		}
    

	return(true);
        }