function check_email (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 matchArray=emailStr.match(emailPat)
        if (matchArray==null) {
                
                //alert("Email address seems incorrect (check @ and .'s)")
                return false
        }

        var user=matchArray[1]
        var domain=matchArray[2]
        if (user.match(userPat)==null) {
                // user is not valid
                //alert("The username doesn't seem to be valid.")
            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 is invalid!")
                                return false
                        }
                 }
                 return true
        }
        // Domain is symbolic name
        var domainArray=domain.match(domainPat)
        if (domainArray==null) {
                //alert("The domain name doesn't seem to be valid.")
                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 address 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="This address is missing a hostname!"
           //alert(errStr)
           return false
        }
         return true;
}