// NOTE:
// This version of e-mail validation returns only a true/false so that the
// end user is not confused by overly-detailed reasons why the e-mail address
// was not valid.
// This function also returns true if emailStr is an empty string.  This leaves
// it up to decide if the e-mail field is required or not.

function emailCheck (emailStr) {
    if (emailStr == "") return true;

    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) return false;

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

    if (user.match(userPat)==null) return false;

    var IPArray=domain.match(ipDomainPat)
    if (IPArray!=null) {
        for (var i=1;i<=4;i++) {
	        if (IPArray[i]>255) {
	            return false;
	        }
        }
        return true;
    }

    var domainArray=domain.match(domainPat)
    if (domainArray==null) 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) {
        return false;
    }

    if (len<2) return false;

    return true;
}