In Pokémon Mystery Dungeon games, you may be referring to:
* A-okay: Perhaps you meant "OK," which is a common abbreviation for "okay" and might be used in dialogue or mission descriptions.
* Mail: This refers to the system where you receive messages from other Pokémon, usually containing helpful information or requests.
* Mystery Mail: This is a special type of mail that contains rare items or other rewards.
If you can provide more context or a specific situation where you heard "a-okay mail," I might be able to help you understand what it refers to.