. mail

You're referring to the postal service!

Here are some common uses of the word "mail":

1. Sending letters or packages: "I'm going to mail this letter to my friend."
2. Checking email: "I need to check my mail to see if I have any new messages."
3. Receiving mail: "I'm waiting for a package to arrive in the mail."
4. Mailbox: "I need to go to the mailbox to pick up my mail."
5. Mail carrier: "The mail carrier delivered a package to my doorstep."

Some other related terms you might find useful:

• Post office: a government-run facility where you can send and receive mail.
• Postmaster: the person in charge of a post office.
• Stamp: a small adhesive label used to pay for postage.
• Envelope: a paper folder used to enclose a letter or document.
• Package: a container used to ship goods or items.

I hope that helps!