Get All Single Sends Stats

**This endpoint allows you to retrieve stats for all your Single Sends.** By default, all of your Single Sends will be returned, but you can specify a selection by passing in a comma-separated list of Single Send IDs as the value of the query string parameter `singlesend_ids`. Responses are paginated. You can limit the number of responses returned per batch using the `page_size` query string parameter. The default is 25, but you specify a value between 1 and 50. You can retrieve a specific...