function enviardados(){
if( document.mailnews1.email.value=="" || document.mailnews1.email.value.indexOf('@')==-1 || document.mailnews1.email.value.indexOf('.')==-1 )
{
alert( "Preencha campo E-MAIL corretamente!" );
document.mailnews1.email.focus();
return false;
}
return true;
}

function clearField(field) {
  // Check if field contains the default value
  if (field.value == field.defaultValue) {
    // It does, so clear the field
    field.value = "";
  }
}

function checkField(field) {
  // Check if user has entered information in the field
  if (field.value == "") {
    // User has not entered anything
    field.value = field.defaultValue;
  }
}