Hello! 
I do not mean to be rude, or have a lack of introduction, but I would like to keep this idea short and professional.
I think that a mailbot-based side quest would be really cool to have, as you could help retrieve lost mail from around the map, deliver mail to certain places, or even unlock a special mailroom-themed area after completing these tasks. This would not be a limited-time event, and could be unlocked at any time.
Some rewards could be:
- The “Mail Bling” Hat or Back Bling (Similar to a vote box-looking thing strapped onto the player)
- The “Keep it Going! At ###” Hub Title (With the number representing how many times the “Mail Bling” has been clicked, making every box unique)
- And finally, the “Mailman Mastery” Hub Title (On quest completion)
Have a good one! 
Marshmello7119