He leka uila kūʻokoʻa ʻo K-9 Mail no ka ʻōnaehana hana Android. Hāʻawi ʻia ia ma ke ʻano he Pūnaehana Android Free/Open Source ma lalo o ka laikini Apache-2.0. Kūʻai ʻia ka papahana ma ke ʻano he hana hou aku no ka palapala leka uila i hoʻokomo ʻia ma ka hapa nui o nā kelepona. Kākoʻo ia i nā pahu leta POP3 a me IMAP a kākoʻo iā IMAP IDLE no nā hoʻolaha manawa maoli.