You might call it a [canned response][1], where *can* is a reference to mass-produced products delivered in tin cans - there is no customisation of its (standard) content once the can is sealed.

The sender might have several canned responses to choose from, but each canned response is a standard reply that isn't tailored to any circumstances.

Canned responses could potentially carry useful information - they are just standardised. If you want to stress the absence of useful information, you might call it a [generic][2] reply (see definition 1b: "lacking specificity").


  [1]: https://en.wikipedia.org/wiki/Canned_response
  [2]: http://www.thefreedictionary.com/generic