""Caging" is a method of voter suppression in which first-class mail is sent to registered voters to confirm their addresses."
No. Caging is a term used in direct mail marketing. A 'form' of caging is used for voter suppression, but that's not the exclusive use of the word.
...else.
But, thanks for the clarification for the audience's sake.
Personally, having spent about 30 years in direct response--among other things--I realize that, just like automated/predictive/broadcast dialing, there are a lot of everyday business marketing applications that are contorted for less-than-noble purposes when it comes to their implementation in the political sector.
Then again, it's my understanding that you're also in this business, so I can understand why you'd be concerned about its precise definition, as well.