Letter writing is an essential part of business communication. A letter is a written message from one party to another.
So, the letter delivering process:
Letter is written and placed by sender in an envelope on which the recipient's address is written.
Then postage stamp bought and attached by sender to the front of the envelope on the top right corner on the front of the envelope.
Their letter is put by sender in a postbox and nothing more/
The postbox is emptied and all the contents to the regional sorting office are taken by the national postal service of the sender's country.
After that, by the sorting office, each letter is sorted by address and postcode and delivered the letters destined for a particular area to that area's post office.
Then, by the local post office, the letters are dispatched to their delivery personnel who them are delivered by to the proper addresses.
This whole process is being depended on how far the sender is from the recipient, and from a day to 3–4 weeks can be taken anywhere by it.
International mail is sent via trains and airplanes to other countries.