Before anything else, thank you for building Stalwart
When a group member sends mail using the group’s address (From: shared@mailbox,com), the message is currently saved only in the submitting user’s /Sent. Other group members never see it. Add a per-Account flag that makes Stalwart APPEND a copy of every send-as-group message to the group’s /Sent server-side, so the behaviour is consistent across every JMAP/IMAP/OWA-like client without any client-side work.
This mirrors Microsoft Exchange’s MessageCopyForSentAsEnabled (shipped Exchange 2013 CU9 / Exchange Online ~2015), which is the de-facto reference UX for shared mailboxes.
Group accounts are already 90 % there: members share Inbox, and after #485 they can submit From: group@. The remaining gap, sent visibility, is what makes shared mailboxes operationally useful: audit, continuity, “who replied to that customer last week”. Without it the feature is half-baked and every operator hits the same wall.
Stalwart is the only layer with all the context: from header, authenticated principal, Group ACL, and putting the logic anywhere else means re-implementing it in every JMAP and IMAP client with all the subtle drift that brings; the audit trail comes along for free since X-Authenticated-User is already stamped on outgoing mail; and the per-user Sieve workaround people reach for today bakes the target mailbox’s id into each member’s script (silently breaks on rename) and turns “add a member” into a three-step ACL + Sieve + identity dance, which the server-side flag collapses back to a single ACL change.
Also, adding bulwarkmail/webmail#61 for reference