function validEMail(field) {
         var period = ".";
         var atsign = "@";
         var ok = "yes";
         var NumPeriod = 0;
         var PosPeriod = 1;
         var NumAtSign = 0;
         var PosAtSign = 0;
         var temp;
         for (var i=0; i<field.value.length; i++) {
                temp = "" + field.value.charAt(i);
                if (atsign.indexOf(temp) != "-1") {
                    NumAtSign++;
                    if (NumAtSign == 1) PosAtSign = i+2;
                }
                if (NumAtSign == 1) {
                   if (period.indexOf(temp) != "-1") {
                       NumPeriod++;
                       if (NumPeriod == 1) PosPeriod = i;
                   }
                }
         }
         if (field.value.length > 0) {
           if (NumAtSign != 1) {
              alert("Invalid eMail Address!");
              field.focus();
              return false;
           }
           if (NumPeriod < 1) {
              alert("Invalid eMail Address!");
              field.focus();
              return false;
           }
           if (PosAtsign > PosPeriod) {
              alert("Invalid eMail Address!");
              field.focus();
              return false;
           }
         }
    }