This confirms that Stalwart’s mailing list implementation delivers to a set of recipients based purely on address expansion; it does not send a header like To/Cc listing all recipients, and there is no built-in “reflector” mode that exposes the full recipient list to subscribers. The MailingList object stores recipients as a flat list, but the server delivers a copy to each recipient individually rather than rewriting headers to show all addresses.
There is no setting (in the WebUI or via stalwart-cli) to make a Stalwart mailing list expose participant addresses to each other. That kind of behavior (a “reflector” list showing all subscribers in To/Cc, common in classic listserv software) isn’t part of the mailing-list feature as documented; Stalwart’s lists just fan a single incoming message out to the stored recipient set. If you need visible participant lists, you’d have to build that with a Sieve script or external mailing-list manager that rewrites headers, since it’s outside of what the built-in MailingList object does.
Docs reference: Mailing lists | Stalwart
This is an automated reply from the Stalwart Help Bot. Other community members may follow up if this answer is incomplete or wrong.
No, there’s no setting for that, in the web UI or over the API. Lists in Stalwart are envelope-level expansion: the message headers pass through untouched and each member gets their own copy addressed to the list, so it behaves like Bcc and members can’t see each other. The original recipient is preserved for filtering purposes but not in anything a mail client displays.
Two ways to get what you want. If the group is small and stable, put the addresses in To or Cc when sending, which most clients support through a contact group. Otherwise you can rewrite the To header at the DATA stage with a trusted Sieve script using editheader (stalw.art/docs/mta/rewrite/headers), but the membership isn’t exposed to Sieve, so you’d be hardcoding the addresses in the script and maintaining them in two places.