FBI
We can't know the answer to your question.
You can't find the sender by using the tracking number. At best you may be able to find out the city it was sent from. Your best bet is to contact the post office and ask who sent it.
If people or business have moved or closed down...the letter can then be returned to sender.
Certified mail requires you to sign for the mail. To know who sent the certified mail, you usually need to sign for it but the sender's name is typically listed on the green card attached to the mail. You can ask to look at the card before signing and if you miss the delivery, you can look at the slip the mail carrier leaves for you that lets you know you had a certified letter or package.
Contact the sender to see if they have a copy.
To the Sender
Just ask the Letter Carrier or Sales Associate, there is no rule that says they can't. Remember the Postal Service is all about Customer Service.
Certified mail is mail that is designed to ensure it gets to its proper recipient. Generally when someone sends a certified letter, he wants to ensure that it gets to the recipient and a receipt signed by the recipient at the time the letter was delivered is sent back to the sender, giving the sender a record that such mail has been delivered.
It don't always show the name of the sender.
FBI
We can't know the answer to your question.
You can't find the sender by using the tracking number. At best you may be able to find out the city it was sent from. Your best bet is to contact the post office and ask who sent it.
If a person is not home to sign for a certified letter, a notice will be lift at their home. A person has 7 days to pick up the letter, before the post office will try again. Two more attempts will be made, before it will be returned to the sender.
You will receive a second notice after 5 days and then the letter is returned to sender 15 days from the date it was received at the post office and is marked unclaimed.
Question is not clear. WHAT letter? Why would the sender have to initial it?
If people or business have moved or closed down...the letter can then be returned to sender.