// check for blank email
 var isChecked = false;

 // Check for blank field
 function isBlank(theField)  {
  if(theField.value.length == 0)
   return true;
  else
   return false;
 }
 function checkForm(form){
  if(isBlank(form.usermail)){
   alert('Please enter an Email Address.');
   form.usermail.focus();
   return false;
  }
}



//Validate email address: 
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) 
{ 
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 IPArray=domain.match(ipDomainPat) 
if (IPArray!=null) 
{ 
for (var i=1;i<=4;i++) 
{ 
if (IPArray[i]>255) 
{ 
alert("Destination IP address is invalid!") 
return false 
} 
} 
return true 
} 

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) 
{ 
alert("The address must end in a three-letter domain, or two letter country.") 
return false 
} 

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

return true; 
}