Resetting your password invalidates all existing sessions as a security measure, which is expected once — but it shouldn't cause repeated logouts afterward. A couple of things that can cause this specifically after a reset:
- A browser extension or privacy tool clearing cookies periodically (ad blockers and some privacy extensions do this).
- Multiple tabs open from before the reset, each holding an old (now invalid) session, fighting with the new one.
Try closing all SubsiMail tabs, clearing cookies for the site specifically, and logging in fresh in a single tab. Let me know if it keeps happening after that.