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 matchArray=emailStr.match(emailPat)
	if (matchArray==null) {
		return "Email address seems incorrect (check @ and .'s)"
	}
	var user=matchArray[1]
	var domain=matchArray[2]

	if (user.match(userPat)==null) {
		return "Email username doesn't seem to be valid."
	}

	var IPArray=domain.match(ipDomainPat)
	if (IPArray!=null) {
		for (var i=1;i<=4;i++) {
			if (IPArray[i]>255) {
				return "Email destination IP address is invalid!" 
			}
		}
		return ""
	}

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

	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 "The email address must end in a three-letter domain, or two letter country."
	}

	if (len<2) {
	var errStr="This email address is missing a hostname!"
	return errStr
	}

	return "";
}