function IsEmailValid(FormName,ElemName)
{
var EmailOk  = true;
var Temp     = document.forms[FormName].elements[ElemName];

//replace leading and trailing whitespace
var cleanString = Temp.value.replace(/^\s+/g, '').replace(/\s+$/g, '');

var AtSym    = cleanString.indexOf('@');
var Period   = cleanString.lastIndexOf('.');
var Space    = cleanString.indexOf(' ');
var Length   = cleanString.length - 1;				// Array is from 0 to length-1

if ((AtSym < 1) ||                     // '@' cannot be in first position
    (Period <= AtSym+1) ||             // Must be at least one valid char btwn '@' and '.'
    (Period == Length ) ||             // Must be atleast one valid char after '.'
    (Space  != -1))                    // No empty spaces permitted
   {  
      EmailOk = false;
      alert('Please enter a valid e-mail address.\n\nYou entered ' + Temp.value + '\n\nPlease use the following format: user@domain.com');
      Temp.value="";
      Temp.focus();
   }
return EmailOk;
}