https://bazaar.launchpad.net/~mailman-coders/mailman/3.0/vie...
Line 56:
_password = Column('password', Unicode)
"To answer the question that at least a few dozen of you are looking for: Mailman 3 will not, by default, send you a monthly reminder that includes your password in plain text. In fact, it can't; Mailman 3 hashes passwords before storing them."
So, it's unfortunate, but it's nothing new.
It is stored in unicode because that's what passlib hash algorithms return, not because there's an underlying plaintext representation.
Encrypting them indicates there's a way to decrypt them. Hashing, by definition, is not possible (not practical, really).
Deleted comment
That's just the storage backend. Encryption is not handled at this layer, but at (e.g.):
https://bazaar.launchpad.net/~mailman-coders/mailman/3.0/vie...