Get All Verified Senders

**This endpoint allows you to retrieve all the Sender Identities associated with an account.** This endpoint will return both verified and unverified senders. You can limit the number of results returned using the `limit`, `lastSeenID`, and `id` query string parameters. * `limit` allows you to specify an exact number of Sender Identities to return. * `lastSeenID` will return senders with an ID number occuring after the passed in ID. In other words, the `lastSeenID` provides a starting poin...