Return to Sender

Return to Sender is an achievement for Halo: Reach multiplayer matchmaking added with the Defiant Map Pack. The achievement is earned by returning your team's flag twice during a Capture the Flag match. It can be earned on any multiplayer map.

Trivia

 * The achievement's name is a reference to the Halo 2 campaign level Cairo Station's last chapter of the same name.
 * As with Crackin' Skulls and Candy from a Baby, this achievement does not actually require the player to be playing matchmaking at all to earn it; It is possible to unlock the achievement while playing custom games, as long as the gametype being played is electronically signed by Bungie. (That is, if the gametype is the same one used in matchmaking.) See here for the specific file.