Understanding the Outbox Model

Learn how Nostr's smart relay system ensures your posts reach everyone who follows you

The Problem: Missing Posts 📬

Have you ever posted something on Nostr, but your friends couldn’t see it? Or followed someone but never saw their posts? This is the discovery problem.

The Old Way (Before Outbox Model)

You Post → Relay A → ❌ Your friend only uses Relay B

Your Friend's View:
❌ "Where did @alice's post go?"

You’d post to your favorite relay, but your followers might be using different relays entirely. They’d never see your content!

The Solution: Outbox Model

The outbox model solves this by advertising where you post. Think of it like leaving a forwarding address.

You: "I post to Relay A, Relay B, and Relay C"
(Stored in your kind:10002 event)

Follower: "Got it! I'll check those relays for @alice's posts"

What Is the Outbox Model? 📮

The outbox model (NIP-65) is like having a public address book that tells everyone where to find your posts.

The Post Office Analogy Extended

Remember relays are like post offices? The outbox model adds a forwarding address system:

Traditional Post Office:

• You have one mailbox at one post office
• If you move, people send mail to the wrong place

Nostr Outbox Model:

• You have a public list of post offices where you receive mail
• If you “move” (switch relays), you update your public list
• Everyone knows where to find you

Your Relay List (kind:10002)

Your Nostr client automatically creates a relay list that tells others:

{
  "kind": 10002,
  "tags": [
    // Relays where you generally post (your "outbox")
    ["r", "wss://relay.nostr.info", "write"],
    ["r", "wss://relay.damus.io", "write"],
    
    // Relays where you read mentions (your "inbox")
    ["r", "wss://nos.lol", "read"],
    ["r", "wss://relay.snort.social", "read"]
  ]
}

Markers explained:

• write → Where you post your content (outbox)
• read → Where you check for mentions/replies (inbox)
• no marker → Both read and write

How It Works in Practice

Scenario 1: Alice Posts, Bob Follows

Alice's Relay List (kind:10002):
  - wss://relay.a.com [write]
  - wss://relay.b.com [write]

Bob follows Alice. Bob's client sees:
  "Check wss://relay.a.com and wss://relay.b.com for Alice's posts"

Result: Bob connects to both relays and sees Alice's content! ✅

Scenario 2: Charlie Mentions Alice

Charlie mentions @alice in a post

Charlie's client checks Alice's relay list:
  - wss://relay.a.com [read]
  - wss://relay.b.com [read]

Charlie's client sends the mention to Alice's READ relays

Result: Alice sees the mention even if she's offline! ✅

Scenario 3: Alice Switches Relays

Alice stops using relay.a.com, starts using relay.c.com

1. Alice updates her kind:10002 relay list
2. Propagates to all connected relays
3. Followers automatically start checking relay.c.com

Result: No lost posts, no manual reconnection needed! ✅

Why This Matters

1. Discovery Without Centralization

Traditional social media has a central server that knows everyone. Nostr is decentralized, so it needs another way to find people.

Outbox model = distributed discovery

2. Censorship Resistance

If one relay blocks you, your followers can still find you through your relay list on other relays.

3. Flexibility

Switch relays anytime without losing your audience. Just update your relay list.

4. Efficiency

Clients only connect to the relays you use, not every relay in existence.

Best Practices

Keep Your List Small

Recommended: 2-4 relays total

Why?

• More relays = more connections = more battery drain
• Diminishing returns after 4 relays
• Most content propagates to popular relays anyway

Mix Read and Write

Good setup:

• 2-3 “write” relays (where you post)
• 1-2 “read” relays (for mentions)

Example:

Write to: Popular relay A, Your personal relay
Read from: Popular relay B (for mentions)

Choose Reliable Relays

Use well-known, reliable relays that:

• Have good uptime
• Store content permanently (not ephemeral)
• Are geographically close (lower latency)

Common Misconceptions

”I need to be on every relay”

Wrong: Being on 20+ relays doesn’t help. Your posts propagate through the network. Stick to 2-4 quality relays.

”If I leave a relay, I lose my followers”

Wrong: Just update your relay list (kind:10002). Followers will automatically check your new relays.

”Private DMs go through the outbox too”

Partially true: NIP-17 (private messages) uses the outbox model for delivery, but with extra encryption.

”I need to manually tell people my relays”

Wrong: Your client publishes your relay list automatically. Followers discover it when they follow you.

Technical Deep Dive (Optional)

How Clients Discover Your Relays

1. Initial follow: When someone follows you, their client requests your kind:10002 event
2. Your relays are revealed: The event contains your relay preferences
3. Ongoing updates: If you change relays, you publish a new kind:10002
4. Propagation: Clients spread relay lists to help discovery

Replaceable Events

kind:10002 is replaceable - only the latest version is kept. This means:

• No historical bloat
• Easy to update
• Simple for clients to manage

Privacy Consideration

Your relay list is public. Anyone can see which relays you use. This is necessary for the system to work, but be aware it’s visible.

Take Action

Check Your Current Relays

Look in your Nostr client settings:

• Which relays are you connected to?
• Are they marked as “read” or “write”?
• Do you have 2-4 total?

Optimize Your Setup

If you have 5+ relays:

• Remove the ones with poor uptime
• Keep your 3-4 favorites
• Make sure at least one is “read” for mentions

Spread the Word

Help others understand:

• Share this guide
• Explain why you can’t see someone’s posts
• Help troubleshoot discovery issues