Delivered parcels can be redelivered after they've been collected

[gnarea]

When a parcel is redelivered before it's been collected, the new parcel would supersede its predecessor per the Relaynet specs. However, they parcel will be deleted once collected, so it's possible for an attacker to redeliver a parcel.

This could lead to replay attacks if private gateways fail to ignore previously-processed, incoming parcels.