Open Mailbox with Raised Flag

Either; the words around it decide. The picture is a U.S.-style household mailbox with a signal flag on its side. The carrier drops letters in; the resident raises the flag to say “there is mail here to collect”. Carriers do not raise it to announce a delivery. Read by the hardware, 📬 is an open box with outgoing mail inside.

Read as a picture in a message, a box with a letter showing looks like mail that has arrived, and next to “check your inbox” that is the reading it carries. The Unicode review of these characters noted the same receiving-or-sending ambiguity. If direction matters, write “arrived” or “ready for pickup” instead of leaving it to the flag.

The four mailbox emoji form a grid of two switches: lid open or closed, flag up or down. 📬 is the open, flag-up corner, and the only one whose usual artwork shows a letter inside.