// Email address checking function gotten from:
// http://javascript.internet.com/forms/check-email.html
function emailCheck (emailStr) {
	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 errStr;

	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)")
		errStr = "~ Email address seems incorrect (check @ and .'s)\n";
		return errStr
	}

	var user=matchArray[1]
	var domain=matchArray[2]

	// See if "user" is valid 
	if (user.match(userPat)==null) {
	    // user is not valid
	    //alert("The email address doesn't seem to be valid.")
		errStr = "~ The email address doesn't seem to be valid.\n";
	    return errStr
	}

	/* 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!")
				errStr = "~ Destination IP address is invalid!\n"
				return errStr
		    }
	    }
	    return true
	}

	// Domain is symbolic name
	var domainArray=domain.match(domainPat)
	if (domainArray==null) {
		//alert("The domain name in the email address doesn't seem to be valid.")
		errStr = "~ The domain name in the email address doesn't seem to be valid.\n"
	    return errStr
	}

	/* 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 is 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>4) {
	   // the address must end in a two letter, three letter or four letter word.
	   //alert("The email address must end in a three-letter domain, or two letter country.")
	   errStr = "~ The email address must end in a three-letter domain, or two letter country.\n";
	   return errStr
	}

	// Make sure there is a host name preceding the domain.
	if (len<2) {
	   errStr = "~ This email address is missing a hostname!\n"
	   //alert(errStr)
	   return errStr 
	}

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