This allows us to thread messages even when we receive them out of
order, or never receive the root.
The thread ids for messages that aren't present but are referred to are
stored as metadata in the database and then retrieved if we ever get
that message.
When determining the thread id for a
This allows us to thread messages even when we receive them out of
order, or never receive the root.
The thread ids for messages that aren't present but are referred to are
stored as metadata in the database and then retrieved if we ever get
that message.
When determining the thread id for a