If your safety relies on privacy, please know that nothing is E2EE and the admins (if they can be fucked to SQL in), LEO with a warrant), or hackers (if they're good at it) can see private forums and DMs.

I don't think Postmill has support for "private" forums, and I don't think I'm alone in browsing jstpst by new posts chronologically.

What you can do is to encrypt your posts now with a private key only you remember, posting gibberish to the frontpage. That would be a new type of Jstpsting I think