diff --git a/src/api/nip05.rs b/src/api/nip05.rs
index bad5d78..0f1b51c 100644
--- a/src/api/nip05.rs
+++ b/src/api/nip05.rs
@@ -40,16 +40,16 @@ use crate::AppState;
 
 // ── constants ─────────────────────────────────────────────────────────────────
 
-/// Default relay hints advertised in the well-known `relays` map.
+/// Fallback interop relay hints, used ONLY when the operator has opted in via
+/// `NIP05_EXTRA_RELAY_HINTS`.
 ///
-/// Public relays shared with other wallets so cross-wallet delivery works before
-/// any per-user relay list is configured. NIP-05 lets a server advertise relay
-/// hints per pubkey in the `relays` object; we serve the same default set for
-/// every resolved name.
-///
-/// TODO(phase-2): make configurable and serve per-user lists (NIP-65 kind 10002
-/// / NIP-17 inbox relays) when private-message delivery lands.
-const DEFAULT_RELAYS: &[&str] = &["wss://relay.damus.io", "wss://nos.lol"];
+/// These are third-party relays. Advertising them unconditionally made every
+/// self-hosted instance publish a document pointing its own users at
+/// damus/nos.lol, so a correspondent would deliver there instead of to the
+/// operator's relay. An operator running a private or air-gapped deployment had
+/// no way to stop their NIP-05 document recommending someone else's
+/// infrastructure. Opt-in only.
+const INTEROP_RELAY_HINTS: &[&str] = &["wss://relay.damus.io", "wss://nos.lol"];
 
 // ── DTOs ──────────────────────────────────────────────────────────────────────
 
@@ -118,18 +118,27 @@ pub async fn well_known_nostr(
 }
 
 /// Relay hints advertised for a resolved pubkey: this instance's own relay (the
-/// user's DM inbox) FIRST when enabled, then the public interop relays so
-/// cross-wallet (e.g. Goblin) delivery still works before any per-user list.
-/// Per-user lists (NIP-65 kind 10002 / NIP-17 inbox relays) remain future work.
+/// user's DM inbox) first, then any interop relays the OPERATOR opted into.
+///
+/// An instance advertises only what its operator chose. Per-user lists (NIP-65
+/// kind 10002 / NIP-17 inbox relays) remain future work.
 fn relay_hints(config: &crate::config::Config) -> Vec<String> {
     let mut hints = Vec::new();
     let r = &config.messaging.relay;
     if r.enabled && !r.advertised_url.trim().is_empty() {
         hints.push(r.advertised_url.clone());
     }
-    for d in DEFAULT_RELAYS {
-        if !hints.iter().any(|h| h == d) {
-            hints.push((*d).to_string());
+    if config.messaging.nip05_interop_hints {
+        for d in INTEROP_RELAY_HINTS {
+            if !hints.iter().any(|h| h == d) {
+                hints.push((*d).to_string());
+            }
+        }
+    }
+    for extra in &config.messaging.nip05_extra_relay_hints {
+        let extra = extra.trim();
+        if !extra.is_empty() && !hints.iter().any(|h| h == extra) {
+            hints.push(extra.to_string());
         }
     }
     hints
diff --git a/src/config.rs b/src/config.rs
index 8a729ca..4d715fd 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -655,6 +655,15 @@ fn parse_premium_plans(s: &str) -> Vec<PremiumPlan> {
 #[derive(Clone)]
 pub struct MessagingConfig {
     pub relay: RelayConfig,
+    /// Advertise the built-in third-party interop relays (damus, nos.lol) in the
+    /// NIP-05 document. OFF by default: an instance should recommend only what
+    /// its operator chose. Turn on for a public deployment that wants
+    /// cross-wallet delivery to work before correspondents publish their own
+    /// relay lists.
+    pub nip05_interop_hints: bool,
+    /// Additional relay URLs to advertise in the NIP-05 document, comma-separated
+    /// in `NIP05_EXTRA_RELAY_HINTS`. Appended after the instance's own relay.
+    pub nip05_extra_relay_hints: Vec<String>,
 }
 
 /// Optional first-party Nostr relay. When `enabled`, the operator runs a relay
@@ -927,6 +936,8 @@ impl Config {
                     retention_days: env_parse("RELAY_RETENTION_DAYS", 30u32)?,
                     write_allowlist: env_list("RELAY_WRITE_ALLOWLIST_NPUBS"),
                 },
+                nip05_interop_hints: env_bool("NIP05_INTEROP_HINTS", false),
+                nip05_extra_relay_hints: env_list("NIP05_EXTRA_RELAY_HINTS"),
             },
             premium: PremiumConfig {
                 enabled: env_bool("PREMIUM_ENABLED", false),
@@ -1527,6 +1538,8 @@ mod tests {
                     retention_days: 30,
                     write_allowlist: Vec::new(),
                 },
+                nip05_interop_hints: false,
+                nip05_extra_relay_hints: Vec::new(),
             },
             premium: PremiumConfig {
                 enabled: false,