Who needs a tracking service when you can just hop on the USPS, FedEx, UPS, or DHL website (or whoever your carrier is) and just track? Maybe you. The Trackthis API integrates an amazing array of functions into your application. The API webpage lists over 10 carriers you can get notifications for.
Founded in 2010 and based in White Plains, NY, Ongage has a simple idea for email marketers: we deliver. It uses different ESPs to deliver mail according to which ones are most likely to succeed in reaching a given email address. Ongage calls this concept "micro-deliverability."