function update(){

	if(document.frmUpdates.email.value == ""){
		alert("E-mail field cannot be left blank.");
		document.frmUpdates.email.focus();
		return false;
	}

	//IsValidEmail() ensures valid e-mail addresses in e-mail field:
	if(!IsValidEmail(document.frmUpdates.email.value)){
		document.frmUpdates.email.focus();
		return false;
	}

	return true;
}

function IsValidEmail(emailfield) {
	var iAt;
	var iAt2;
	var iPeriod;
	var iSpace;
	var iLength;
	var sFirstChar;
	var sLastChar;
	var pattern;
	var res;
	var field = new String(emailfield);

	iAt = field.indexOf("@", 1);
	iLength = field.length;
	sFirstChar = field.substring(0,1);
	sLastChar = field.substring(iLength-1, iLength);

	if(field.indexOf("..") > 0) {
		alert("Please correct the e-mail address.  Two periods together are not allowed.");
 		return false;
	}
	if(field.indexOf(".@") > 0) {
		alert("Please correct the e-mail address.  A period can not preceed the @ symbol.");
 		return false;
	}
	if(iAt == -1) {
		alert("Please correct the e-mail address. An @ is required.");
		return false;
	}
	iAt2 = field.indexOf("@", iAt + 1);
	if(iAt2 != -1) {
		alert("Please correct the e-mail address.  There can be only one @ symbol.");
 		return false;	
	}
	iPeriod = (field.indexOf(".", iAt + 1));
	if(iPeriod == -1) {
		alert("Please correct the e-mail address.  A period is required.");
 		return false;
	}
	if(iPeriod == (iAt+1)) {
		alert("Please correct the e-mail address.  A period can not follow the @ symbol.");
 		return false;
	}
	if(iPeriod == (iAt-1)) {
		alert("Please correct the e-mail address.  A period can not preceed the @ symbol.");
 		return false;
	}
  	iSpace = (field.indexOf(" ", 1));
  	if(iSpace > 0) {
    		alert("Please correct the e-mail address. No spaces are permitted.");
    		return false;
  	}
	pattern = new RegExp("[0-9a-zA-Z]");
	if (!sFirstChar.match(pattern)) {
		alert("Please correct the e-mail address. The first character must be a letter or number.");
		return false;
	}
	if (!sLastChar.match(pattern)) {
		alert("Please correct the e-mail address. The last character must be a letter or number.");
		return false;
	}
	if (iLength < 5) {
		alert("Please correct the e-mail address. It should conform to name@aaa.bbb");
		return false;
	}
	var validchars = new String("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789.-_@");
	for (i=0; i<field.length; i++) {
		j = validchars.indexOf(field.charAt(i), 0);
		if (j < 0) {
			alert("Please correct the e-mail address. Special characters are not allowed. Use only letters, numbers, @, period, underscore and hyphen characters.");
			return false;
		}
	}
	return true;
}//IsValidEmail