function chkInput () {
        if (document.contact.name.value == "") {
          alert("Please enter your name.");
          document.contact.name.focus();
          return false;
        }
        if (document.contact.email.value == "") {
          alert("Please enter your e-mail address.");
          document.contact.email.focus();
          return false;
        }
        if (document.contact.subject.value == "") {
          alert("Please enter a short descriptive subject regarding your request.");
          document.contact.subject.focus();
          return false;
        }
        return emailCheck (document.contact.email.value);
      }

      function emailCheck (emailStr) {
      /* Thanks to http://javascriptsource.com for this funktion ! */
      /* The following pattern is used to check if the entered e-mail address
         fits the user@domain format.  It also is used to separate the username
         from the domain. */
      var emailPat=/^(.+)@(.+)$/
      /* The following string represents the pattern for matching all special
         characters.  We don't want to allow special characters in the address. 
         These characters include ( )  > @ , ; : \ " . [ ]    */
      var specialChars="\\(\\)>@,;:\\\\\\\"\\.\\[\\]"
      /* The following string represents the range of characters allowed in a 
         username or domainname.  It really states which chars aren't allowed. */
      var validChars="\[^\\s" + specialChars + "\]"
      /* The following pattern applies if the "user" is a quoted string (in
         which case, there are no rules about which characters are allowed
         and which aren't; anything goes).  E.g. "jiminy cricket"@disney.com
         is a legal e-mail address. */
      var quotedUser="(\"[^\"]*\")"
      /* The following pattern applies for domains that are IP addresses,
         rather than symbolic names.  E.g. joe@[123.124.233.4] is a legal
         e-mail address. NOTE: The square brackets are required. */
      var ipDomainPat=/^\[(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\]$/
      /* The following string represents an atom (basically a series of
         non-special characters.) */
      var atom=validChars + '+'
      /* The following string represents one word in the typical username.
         For example, in john.doe@somewhere.com, john and doe are words.
         Basically, a word is either an atom or quoted string. */
      var word="(" + atom + "|" + quotedUser + ")"
      // The following pattern describes the structure of the user
      var userPat=new RegExp("^" + word + "(\\." + word + ")*$")
      /* The following pattern describes the structure of a normal symbolic
         domain, as opposed to ipDomainPat, shown above. */
      var domainPat=new RegExp("^" + atom + "(\\." + atom +")*$")
      
      
      /* Finally, let's start trying to figure out if the supplied address is
         valid. */
      
      /* Begin with the coarse pattern to simply break up user@domain into
         different pieces that are easy to analyze. */
      var matchArray=emailStr.match(emailPat)
      if (matchArray==null) {
        /* Too many/few @'s or something; basically, this address doesn't
           even fit the general mould of a valid e-mail address. */
        alert("Email address seems incorrect (check @ and .'s)")
        document.contact.email.focus();
        return false
      }
      var user=matchArray[1]
      var domain=matchArray[2]
      
      // See if "user" is valid 
      if (user.match(userPat)==null) {
          // user is not valid
          alert("The username of your email doesn't seem to be valid.")
          document.contact.email.focus();
          return false
      }
      
      /* if the e-mail address is at an IP address (as opposed to a symbolic
         host name) make sure the IP address is valid. */
      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 of your email is invalid!")
                document.contact.email.focus();
                return false
            }
          }
          return true
      }
      
      // Domain is symbolic name
      var domainArray=domain.match(domainPat)
      if (domainArray==null) {
          alert("The domain name of your email doesn't seem to be valid.")
          document.contact.email.focus();
          return false
      }
      
      /* domain name seems valid, but now make sure that it ends in a
         three-letter word (like com, edu, gov) or a two-letter word,
         representing country (uk, nl), and that there's a hostname preceding 
         the domain or country. */
      
      /* 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].length2 || 
          domArr[domArr.length-1].length>3) {
         // the address must end in a two letter or three letter word.
         alert("The email address must end in a three-letter domain, or two letter country.")
         document.contact.email.focus();
         return false
      }
      
      // Make sure there's a host name preceding the domain.
      if (len2) {
         var errStr="This email address is missing a hostname!"
         alert(errStr)
         document.contact.email.focus();
         return false
      }
      
      // If we've gotten this far, everything's valid!
      return true;
      }