Digital nomads: How do you physcially mail documents?

Many times companies ask you to sign a document and mail it to their office.

Is there any app or service thru which we can drop a document at nearest post office and get all tracking info on the app?

Not all carriers are available in all countries.

Every service has their own website, different charges and if you work from multiple cities, it soon become very difficult to track the status of these consignments.