In India we usually use the term post/letter, and use "mail" as abbr for email. But here people use "mail" for postal and "email" for email.
Recently i had to mail to Philadelphia. So i found a postal office nearby my home and went very early to avoid queues (their timings is 8:30 am to 5pm). From the day 1 in USA, i never sent any mail. So no idea whats the procedure.
When i went inside, there was an employee in the counter. I just went to him and told i need send the mail. He gave me options like normal, priority etc. I chose for priority coz that was very important mail. The normal mail was 0.69 cents. But the priority mail was $3.8, where we can track the mail and get acknowledgement as the person who receives it has to sign.
That person gave me the envelope which had stamp on it and asked me to fill the address and get it back. I wrote the TO address in the front of the envelope and FROM address at back of the envelope. When i gave the envelope to him , he was quite puzzled. He showed me a sample of letter and asked why i did not write the FROM address in the front side of the envelope. Then i just explained my situation, that this was first mail ever im sending in USA, so no idea on where to write the address.
Below is the format of writing address in USA.