I think this is technically a custom bounce-back message because you replied to their default "do not reply" address. This is a great approach - especially ove

I think this is technically a custom bounce-back message because you replied to their default "do not reply" address. This is a great approach - especially over sending a standard bounce with an error like most mail servers are setup with by default. Plus, this goes back to a past argument about whether to use do-not-reply addresses at all, and since it's very difficult to get around, this is a nice approach.