It’s not documented as a built‑in, declarative option (e.g. “only record when UTM source = X”), but you can achieve this behavior using manual start/stop of Session Replay in your own code.
On Web, you can:
1. Initialize Mixpanel with record_sessions_percent: 0 so nothing is recorded by default.
2. In your app, read the UTM parameters from the URL.
3. If the condition matches (e.g. utm_source contains XYZ), call mixpanel.start_session_recording() to force recording on; otherwise, do nothing.
start_session_recording() “forces recording to begin, regardless of the record_sessions_percent init option,” and is explicitly recommended for cases like “only record certain types of users” or “only record users utilizing certain features.”[JS replay capture]
Example pattern (pseudo‑code):
```
js
mixpanel.init('<YOUR_PROJECT_TOKEN> ', {
record_sessions_percent: 0 // default: no sessions recorded
});
// after init, once you can read URL params:
const params = new URLSearchParams(window.location.search);
const utmSource = params.get('utm_source') || '';
if (utmSource.includes('XYZ')) {
mixpanel.start_session_recording();
}
LBKSYou can similarly call `mixpanel.stop_session_recording()` when a user navigates to areas you don’t want recorded.[[JS replay capture](https://docs.mixpanel.com/docs/tracking-methods/sdks/javascript/javascript-replay#capturing-replays); [Replay privacy controls](https://docs.mixpanel.com/docs/session-replay/session-replay-privacy-controls#disabling-replay-collection)]
The docs do not mention UTM‑based conditions specifically, but they do support this general “only record certain users/contexts” pattern via manual start/stop.
