function checknumber() {
if (event.keyCode<=57 && event.keyCode>=48) return true;
if (event.keyCode==44 || event.keyCode==46) return true;
return false;
}

function checkemail (emailStr) {
var emailPat=/^(.+)@(.+)$/
var specialChars="\\(\\)<>@,;:\\\\\\\"\\.\\[\\]"
var validChars="\[^\\s" + specialChars + "\]"
var quotedUser="(\"[^\"]*\")"
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) {
    alert("The username doesn't seem to be valid.")
    return false
}

var domainArray=domain.match(domainPat)
if (domainArray==null) {
    alert("The domain name doesn't seem to be valid.")
    return false
}

/* 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.
   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;
}