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. */
		return false;
	    }
	    var user=matchArray[1]
	    var domain=matchArray[2]

	    // See if "user" is valid 
	    if (user.match(userPat)==null) 
	    {
		// user is not 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)
		{
		    return false;
		}
	      }
	      return true;
	    }

	    // Domain is symbolic name
	    var domainArray=domain.match(domainPat)
	    if (domainArray==null) 
	    {
		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
	    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.
		return false;		    
	    }

	    // Make sure there's a host name preceding the domain.
	    if (len<2) 
	    {
		return false;		    
	    }

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