<!-- This script and many more are available free online at -->
<!-- The JavaScript Source!! http://javascript.internet.com -->

function emailCheck (emailStr) 
{
	var error='';
	var checkTLD=1;
	var knownDomsPat=/^(com|net|org|edu|int|mil|gov|arpa|biz|aero|name|coop|info|pro|museum|cat|mobi)$/;
	var emailPat=/^(.+)@(.+)$/;
	var specialChars='\\(\\)><@,;:\\\\\\\"\\.\\[\\]';
	var validChars="\[^\\s" + specialChars + "\]";
	var quotedUser="(\"[^\"]*\")";
	var ipDomainPat=/^\[(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\]$/;
	var atom=validChars + '+';
	var word="(" + atom + "|" + quotedUser + ")";
	var userPat=new RegExp("^" + word + "(\\." + word + ")*$");
	var domainPat=new RegExp("^" + atom + "(\\." + atom +")*$");
	var matchArray=emailStr.match(emailPat);

	if (matchArray==null) 
	{
		error +="Email address seems incorrect (check @ and .'s)\n";
		return error;
	}
	var user=matchArray[1];
	var domain=matchArray[2];

	for (i=0; i<user.length; i++) 
	{
		if (user.charCodeAt(i)>127) 
		{
			error +="The e-mail address contains invalid characters.\n";
			return error;
		}
	}
	for (i=0; i<domain.length; i++) 
	{
		if (domain.charCodeAt(i)>127) 
		{
			error +="This domain name contains invalid characters.\n";
			return error;
		}
	}
	if (user.match(userPat)==null) 
	{
		error +="The e-mail address doesn't seem to be valid.\n";
		return error;
	}

	var IPArray=domain.match(ipDomainPat);
	if (IPArray!=null) 
	{
		for (var i=1;i<=4;i++) 
		{
			if (IPArray[i]>255) 
			{
				error +="Destination IP address is invalid!\n";
				return error;
			}
		}
		return true;
	}

	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) 
		{
			error +="The domain name does not seem to be valid.\n";
			return error;
		}
	}

	if (checkTLD && domArr[domArr.length-1].length!=2 && domArr[domArr.length-1].search(knownDomsPat)==-1) 
	{
		error +="The address must end in a well-known domain or two letter " + "country.\n";
		return error;
	}

	if (len<2) 
	{
		error +="This address is missing a hostname!\n";
		return error;
	}
	return error;
}