A curbside mailbox (letterbox, postbox) with its signal flag lowered and its slot empty. Generally depicted in blue or gray with a red flag. Used for various content concerning postal deliveries and email.
Indicates in the United States that outgoing mail has been picked up. May also indicate that no incoming mail has been delivered.
Compare 📫 Closed Mailbox With Raised Flag, 📪 Closed Mailbox With Lowered Flag, and 📬 Open Mailbox With Raised Flag.
Open Mailbox With Lowered Flag was approved as part of Unicode 6.0 in 2010 and added to Emoji 1.0 in 2015.