When you mail a letter from your mailbox, what kind of mail service does the Mailman Use?

Hey, I have a question. See I usually don't mail letters and things. I mailed a letter today. I placed the letter in my mailbox, and put the red lever in the up position. The mailman proceeded to pick up the letter, and drop the letter off. Now here comes my question. When the mailman takes that letter back to the office, is it mailed that day? And when it is mailed, is it mailed using express mail(the overnight process)?When you mail a letter from your mailbox, what kind of mail service does the Mailman Use?
No its considered as first class mail. It may get to its destination the next day depending on the zipcode its being sent.Your mail can take up to seven days to get there.

If you needed it to get there faster your other option could have been Priority mail ehich may take 2-3 days unless you use carriers like fedex or ups which offers overnite service.