<!-- Version 1.1:  Santanu Nandi(santanu.nandi@gmail.com)-->
function validateEmailCheck (emailStr) {
var emailPat=/^(.+)@(.+)$/

var specialChars="\\(\\)<>@,;:\\\\\\\"\\.\\[\\]"

var validChars="\[^\\s" + specialChars + "\]"

var firstChars=validChars

var quotedUser="(\"[^\"]*\")"

var ipDomainPat=/^\[(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\]$/

var atom="(" + firstChars + 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) {  
	alert('Email address seems incorrect(check @ and .).');
	return false
}
var user=matchArray[1]
var domain=matchArray[2]

if (user.match(userPat)==null) {
    alert('The username of the email address is invalid.');
    return false;
}

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 of email address is invalid.');
		return false;
	    }
    }
    return true
}

// Domain is symbolic name
var domainArray=domain.match(domainPat)
if (domainArray==null) {
    alert('The domain name of the email address is invalid.');
    return false;
}

var atomPat=new RegExp(atom,"g")
var domArr=domain.match(atomPat)
var len=domArr.length
if (domArr[domArr.length-1].length<2 || 
    domArr[domArr.length-1].length>3) {
   // the address must end in a two letter or three letter word.
   alert('The email address must end in a three-letter domain, or two letter country.');
   return false;
}

if (domArr[domArr.length-1].length==3 && len<2) {
   var errStr = 'This email address is missing a hostname.';
   alert(errStr)
   return false
}
// If we've gotten this far, everything's valid!
return true;
}