You can't. The only tracked mail is if you pay extra to have a tracking number on it.
Yes
Hogwarts doesn't exist, they have not sent you a letter which means it cannot be lost in the mail.
44 cents
42 cent for an ordinary first class letter.
It depends. What is regular mail? UPS? Fed-Ex? Is it a letter? Or is it a package?
For a regular letter, two.
Current postage for a regular 1-oz. letter costs 44 cents.
1 to 14 days or more
You can... but I wouldn't. It goes through machines whenever you put it in a regular envelope & if its not flat... it could rip it & your key could get lost somewhere. I used to work with the 1800askusps.
First class mail is delivered in 3 to 5 days
7-10 business days depending on the weather, regular mail.
First Class Mail is delivered in three to five days.