Occupant Mute Synchronization

Occupant Mute Synchronization Allows synchronizing a list of muted group chat participants between multiple clients. This XMPP Extension Protocol is copyright © 1999 – 2024 by the XMPP Standards Foundation (XSF). Permission is hereby granted, free of charge, to any person obtaining a copy of this specification (the "Specification"), to make use of the Specification without restriction, including without limitation the rights to implement the Specification in a software program, deploy the Specification in a network service, and copy, modify, merge, publish, translate, distribute, sublicense, or sell copies of the Specification, and to permit persons to whom the Specification is furnished to do so, subject to the condition that the foregoing copyright notice and this permission notice shall be included in all copies or substantial portions of the Specification. Unless separate permission is granted, modified works that are redistributed shall not contain misleading information regarding the authors, title, number, or publisher of the Specification, and shall not claim endorsement of the modified works by the authors, any organization or project to which the authors belong, or the XMPP Standards Foundation. ## NOTE WELL: This Specification is provided on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, express or implied, including, without limitation, any warranties or conditions of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. ## In no event and under no legal theory, whether in tort (including negligence), contract, or otherwise, unless required by applicable law (such as deliberate and grossly negligent acts) or agreed to in writing, shall the XMPP Standards Foundation or any author of this Specification be liable for damages, including any direct, indirect, special, incidental, or consequential damages of any character arising from, out of, or in connection with the Specification or the implementation, deployment, or other use of the Specification (including but not limited to damages for loss of goodwill, work stoppage, computer failure or malfunction, or any and all other commercial damages or losses), even if the XMPP Standards Foundation or such author has been advised of the possibility of such damages. This XMPP Extension Protocol has been contributed in full conformance with the XSF's Intellectual Property Rights Policy (a copy of which can be found at <https://xmpp.org/about/xsf/ipr-policy> or obtained by writing to XMPP Standards Foundation, P.O. Box 787, Parker, CO 80134 USA). xxxx ProtoXEP Standards Track Standards Council mute Matthew Wild mwild1@gmail.com me@matthewwild.co.uk 0.0.1 2026-03-31 mjw

For blocking remote users, XMPP already supports Blocking Command (XEP-0191) XEP-0191: Blocking Command <https://xmpp.org/extensions/xep-0191.html>. which uses a shared account-wide blocklist. However, in the context of group chats this is inadequate - it would allow blocking the entire group chat (which is sometimes useful) but does not allow reliably blocking individual participants within a chat.

This specification describes a mechanism through which a user can block (also called 'muting' or 'ignoring') a group chat participant and have this synchronized across all their clients.

Allow a user to mute a participant in a way that works reliably across all their devices
Muting should work even in semi-anonymous chats where the user does not know the participant’s real JID
It should work even if the muted participant rejoins or changes their nickname
Past messages should be able to be hidden retrospectively
The ability for clients to show that a message was sent to the chat from a muted participant (without showing the message contents)
Clients should be able to selectively reveal the contents of such messages (if the user requests that)

To achieve these things, the protocol relies on client-side muting based on Anonymous unique occupant identifiers for MUCs (XEP-0421) XEP-0421: Anonymous unique occupant identifiers for MUCs <https://xmpp.org/extensions/xep-0421.html>. with synchronization via PEP Native Bookmarks (XEP-0402) XEP-0402: PEP Native Bookmarks <https://xmpp.org/extensions/xep-0402.html>.

To add a new mute, the client updates the XEP-0402 bookmark for the group chat to include a <muted/> element qualified by the 'urn:xmpp:muted:0' namespace in the <extensions/> element of the bookmark.

The <muted/> element contains zero or more <mute/> elements. Each <mute/> element MUST have an 'id' attribute set to the XEP-0421 occupant identifier of an occupant that is to be muted.

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Clients SHOULD maintain a local list of muted participants in each group chat and keep it synchronized with the bookmarks (publishing local changes, and reacting to changes received from other clients).

If the <muted/> element becomes empty, it SHOULD be removed from the bookmark. Clients receiving bookmarks with an empty or absent <muted/> element MUST assume there are no muted participants within that chat.

There are no significant accessibility considerations for this protocol. This XEP does not mandate any particular UI for how messages from muted participants are handled. However, some guidance is provided to aid consistency between implementations and reduce the potential for confusion.

In general, clients SHOULD display an indication that a message was received (but not displayed) from a muted participant, to reduce confusion when conversations between other users and the muted participant occur.

Clients MAY also provide a way for a user to temporarily reveal the contents of a muted message, to provide necessary context.

Clients SHOULD retroactively hide messages from muted participants, and similarly unhide them when a participant is unmuted.

None.

Alternative approaches were considered but rejected. Some users have tried using XEP-0191 to block occupant JIDs, and implementations have been tweaked to ensure this works as well as it can. However, this approach has several problems:

If servers reply with error bounces to blocked messages, this bounce can be interpreted as a delivery error by the group chat server, and result in the user being kicked from the chat.
While live messages are blocked by XEP-0191, they may still be fetched by clients from the history (e.g. via XEP-0313).
Blocks are based on nickname, and therefore can be bypassed when the blocked participant changes their nickname.
Client ability to retroactively apply/remove blocks or temporarily reveal blocked messages are not possible with blocking.

Server-side muting (in the group chat server or the user’s own server) was considered, but has similar issues relating to history availability, reliable sync, and so on.

The final approach that was considered was a separate PEP node for mutes. However, mutes are scoped to a group chat already by the way that occupant IDs are. This means it makes sense to store a per-chat list of mutes. We already have per-chat information storage in XEP-0402, so it made a lot of sense to move this information into the bookmark to avoid the two stores getting out of sync.

A downside of the approach used in this specification is that you can’t sync mutes for a chat without having a bookmark for it. This generally seems to be a non-issue, as practically all modern clients already automatically create bookmarks for chats they join as a matter of course, to ensure consistency across restarts and across clients.