function emailCheck (emailStr) {

/* 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("An email address is incorrect (check @ and .'s)") 
	return false;
}
var user=matchArray[1]

var domain=matchArray[2]

// See if "user" is valid 

if (user.match(userPat)==null) {

    // user is not valid

    alert("An email address is incorrect.")
    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("An email address in incorrect. \nDestination IP address is invalid!")
		return false;
	    }
    }
    return true
}

// Domain is symbolic name

var domainArray=domain.match(domainPat)

if (domainArray==null) {
	alert("An email address in incorrect.\n A domain name doesn't seem to be valid.")
    return false;
}

/* domain name seems valid, but now make sure that it ends in a
   three-letter word (like com, edu, gov) or a two-letter word,
   representing country (uk, nl), and that there's a hostname preceding 
   the domain or country. */

/* Now we need to break up the domain to get a count of how many atoms
   it consists of. */

var atomPat=new RegExp(atom,"g")

var domArr=domain.match(atomPat)

var len=domArr.length

var xdomain=domArr[domArr.length-1]

// if (xdomain.length <2) {
//    return false;
// }

if (   (xdomain.length < 2) ||
       
       (xdomain.length > 2) &&

       (  xdomain != "net") && 
       (  xdomain != "com") &&
       (  xdomain != "org") &&
       (  xdomain != "gov") &&
       (  xdomain != "edu") &&
       (  xdomain != "biz") &&
       (  xdomain != "info") &&
       (  xdomain != "name") &&
       (  xdomain != "museum") &&
       (  xdomain != "coop") &&
       (  xdomain != "aero") &&
       (  xdomain != "pro") &&
       (  xdomain != "mil") &&
       (  xdomain != "int")


   )
 	{
   
   // the address must end in a two letter or three letter word.

//   alert("Email addresses must end in a three-letter domain, or two letter country.")



   return false;


}

// Make sure there's a host name preceding the domain.

if (len<2) {
   var errStr="An email address is missing a hostname!"
   alert(errStr)
   return false;
}

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


function emailValidate() {

var xemail= window.document.forms[0].xemail.value;

if (emailCheck(xemail) == false) {
       return false; 
} else {
return true;
}
}