function validEmail() {
	var str = document.getElementById("email").value;

	if (!emailCheck(str)) {
		//alert("Email address appears to be incorrect.\nPlease correct and continue.");
		document.getElementById("email").focus();
		return false;
	} else {
		return true;
	}
}	

function emailCheck(emailStr) {
	/* The following variable tells the rest of the function whether or not to verify that the address ends in a two-letter country or well-known TLD.  1 means check it, 0 means don't. */
	var checkTLD=1;

	/* The following is the list of known TLDs that an e-mail address must end with. */
	var knownDomsPat=/^(com|net|org|edu|int|mil|gov|arpa|biz|aero|name|coop|info|pro|museum)$/;

	/* The following pattern is used to check if the entered e-mail address fits the user@domain format.  It also is used to separate the username from the domain. */
	var emailPat=/^(.+)@(.+)$/;

	/* The following string represents the pattern for matching all special characters.  We don't want to allow special characters in the address. 
	These characters include ( ) < > @ , ; : \ " . [ ] */
	var specialChars="\\(\\)><@,;:\\\\\\\"\\.\\[\\]";

	/* The following string represents the range of characters allowed in a 
	username or domainname.  It really states which chars aren't allowed.*/
	var validChars="\[^\\s" + specialChars + "\]";

	/* The following pattern applies if the "user" is a quoted string (in which case, there are no rules about which characters are allowed and which aren't; anything goes).  E.g. "jiminy cricket"@disney.com is a legal e-mail address. */
	var quotedUser="(\"[^\"]*\")";

	/* The following pattern applies for domains that are IP addresses, rather than symbolic names.  E.g. joe@[123.124.233.4] is a legal e-mail address. NOTE: The square brackets are required. */
	var ipDomainPat=/^\[(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\]$/;

	/* The following string represents an atom (basically a series of non-special characters.) */
	var atom=validChars + '+';

	/* The following string represents one word in the typical username. For example, in john.doe@somewhere.com, john and doe are words. Basically, a word is either an atom or quoted string. */
	var word="(" + atom + "|" + quotedUser + ")";

	// The following pattern describes the structure of the user
	var userPat=new RegExp("^" + word + "(\\." + word + ")*$");

	/* The following pattern describes the structure of a normal symbolic domain, as opposed to ipDomainPat, shown above. */
	var domainPat=new RegExp("^" + atom + "(\\." + atom +")*$");

	/* Finally, let's start trying to figure out if the supplied address is valid. */

	/* Begin with the coarse pattern to simply break up user@domain into different pieces that are easy to analyze. */
	var matchArray=emailStr.match(emailPat);

	if (matchArray==null) {
		/* Too many/few @'s or something; basically, this address doesn't even fit the general mould of a valid e-mail address. */
		alert("Email address seems incorrect (check @ and .'s)"); return false; } var user=matchArray[1]; var domain=matchArray[2];

		// Start by checking that only basic ASCII characters are in the strings (0-127).
		for (i=0; i<user.length; i++) {
			if (user.charCodeAt(i)>127) {
				alert("Ths username contains invalid characters.");
				return false;
		   }
		}
		for (i=0; i<domain.length; i++) {
			if (domain.charCodeAt(i)>127) {
				alert("Ths domain name contains invalid characters.");
				return false;
		   }
		}

		// See if "user" is valid 
		if (user.match(userPat)==null) {
			// user is not valid
			alert("The username doesn't seem to be valid.");
			return false;
		}

		/* if the e-mail address is at an IP address (as opposed to a symbolic host name) make sure the IP address is valid. */
		var IPArray=domain.match(ipDomainPat);
		if (IPArray!=null) {
			// this is an IP address
			for (var i=1;i<=4;i++) {
				if (IPArray[i]>255) {
					alert("Destination IP address is invalid!");
					return false;
			   }
			}
			return true;
		}

	// Domain is symbolic name.  Check if it's valid.
	var atomPat=new RegExp("^" + atom + "$");
	var domArr=domain.split(".");
	var len=domArr.length;
	for (i=0;i<len;i++) {
		if (domArr[i].search(atomPat)==-1) {
			alert("The domain name does not seem to be valid.");
			return false;
	   }
	}

	/* domain name seems valid, but now make sure that it ends in a known top-level domain (like com, edu, gov) or a two-letter word, representing country (uk, nl), and that there's a hostname preceding 
	the domain or country. */
	if (checkTLD && domArr[domArr.length-1].length!=2 && domArr[domArr.length-1].search(knownDomsPat)==-1) {
		alert("The address must end in a well-known domain or two letter " + "country."); return false; }

	// Make sure there's a host name preceding the domain.
	if (len<2) {
		alert("This address is missing a hostname!");
		return false;
	}

	// If we've gotten this far, everything's valid!
	return true;
}