Joke Collection Website - Public benefit messages - Why is the arrow in the upper right corner of N78 always there?

Why is the arrow in the upper right corner of N78 always there?

This arrow represents the outbox.

Information that is being sent or delayed without being sent will be temporarily stored in the Outbox, so this symbol will appear.

After the short message is sent, it will automatically go to "Sent Message" and the symbol will disappear.