What Muse does with your messages
Read from Meta's published security write-up for Muse on 2026-09-08, and quoted rather than paraphrased. It trains on your conversations unless you turn that off. Your messages are carried by Meta.
What the document says
| Trains on your conversations | Yes, with opt-out |
|---|---|
| Data of people who never signed up | Not addressed |
| If you cancel | Not addressed |
| Model providers named | Meta |
| Who carries the messages | Meta |
| Where to report a hole | Published |
| Jurisdiction | Not stated |
In its own words
“If you do not want your data to be used in model training at all, you can opt-out via a simple switch in Muse settings.”
What it does not answer
The policy is silent on data of people who never signed up, if you cancel and jurisdiction. Silence is not a denial, and it is not a promise either: a document that does not address the people in your group thread has not agreed to anything about them.
Back to the Muse listing, or see every policy in this directory read the same way, where 9 of 41 name who holds your messages and the rest do not.