Unseenet Working Group                                     A. Lorensen
UN-RFC: 0012                                              October 2026
Category: Standards Track
Status: Draft
Updates: 0002, 0004, 0005

            Unseenet: Retention, Archive Nodes and History

Abstract¶

This document separates two things that UN-RFC 0002 and 0004 mix: how long a post travels between nodes, and how long a node keeps it. Posts travel only within a bounded replication window, so the network never carries old traffic. Archive nodes may keep posts much longer and serve them to readers, and owners and authors can ask archives not to keep their posts.

1. Motivation¶

Without a bound, a network that runs for years would keep offering old posts to every new node and peer, and storage would only grow. With a bound and nothing else, history would simply disappear. Usenet solved this with expiry on ordinary servers and a few archives (and the X-No-Archive header for people who did not want to be archived). This document does the same.

2. Terms¶

Replication window : The age up to which a post is accepted from others and passed on.

Retention : How long a node keeps a post before deleting it.

For an ordinary node they are the same. For an archive node, retention is longer.

3. Replication Window¶

The replication window of a group at a node is

window = min( node retention_days, group retention_days )

where the group value is the manifest's retention_days (UN-RFC 0004 section 3.1, default 90).

A node MUST reject an article whose Date is older than the window, and MUST NOT offer such an article to peers. This is what keeps old posts from circulating: whatever happens, nothing older than the window moves between nodes (except under section 5.3).

The retention_days of a manifest is therefore the owner's statement of how long posts should circulate. UN-RFC 0004 called it a suggestion; this document makes it binding for replication and advisory for archives.

4. Ordinary Nodes¶

An ordinary node deletes articles once they are older than the window, and keeps their Message-IDs in its history at least two days longer (UN-RFC 0005 section 5.4). Manifests and key control articles are never deleted while the group is carried.

5. Archive Nodes¶

5.1 Keeping Posts¶

An archive node keeps articles longer than the window - possibly forever - and serves them to readers with the ordinary commands (GROUP, ARTICLE, LISTGROUP). It announces this with "archive": true in its node information (UN-RFC 0011).

Closed-group and inbox articles are archived as received, i.e. encrypted.

5.2 Opting Out¶

A manifest field "archive": false asks archive nodes to keep the group's posts no longer than its window.
An article header No-Archive: yes asks the same for that article. The header is covered by the signature, so only the author can set it.

Archive nodes MUST honor both. This cannot be enforced technically - anybody can copy what they can read - but it is a clear statement of the author's and owner's wishes, and well-behaved software follows it. Archive operators SHOULD state their adherence in their policy.

5.3 Backfilling Between Archives¶

Two archive nodes MAY exchange old articles to fill each other's gaps. This MUST be explicitly configured on both sides for that peer (an "archive peering"), and only then is the replication window waived for articles received from that peer. Such articles MUST NOT be passed on to ordinary peers.

Archive peering uses the pull method of UN-RFC 0005 section 5.3 with NEWNEWS and ARTICLE. A later document may define a more efficient range transfer.

6. Reading History¶

A client that wants older posts than its node holds can connect to an archive node and read the group there. Because article numbers are local to each node, the client identifies posts by Message-ID when combining what it reads from several nodes.

7. Considerations¶

Archives make history durable, which is valuable and also a risk to people who later regret what they wrote. Section 5.2 gives authors a choice; clients SHOULD make No-Archive easy to set, and MAY set it by default in some groups.
An archive of closed groups protects nothing new and exposes nothing new: it holds ciphertext that only past and present members can read. It does mean that a compromised group secret exposes the archived history of that epoch.