help: Document new direct message permissions settings.

help/restrict-direct-messages.md

@@ -2,37 +2,71 @@
 
 {!admin-only.md!}
 
-In Zulip, users can exchange direct messages with other users,
-[bots](/help/bots-overview) and themselves. Organization
-administrators can configure who is allowed to use direct messages.
+Organization administrators can configure two types of permissions for [direct
+messages](/help/direct-messages):
 
-## Configure who can use direct messages
+- Who can **authorize** a direct message conversation. To send a DM, the recipients
+  must include at least one user who can authorize the conversation (the sender
+  or someone else).
+- Who can **start** a direct message conversation.
 
-!!! warn ""
+These settings are designed so that users can always respond to a direct message
+they've received (unless organization permissions change). They also provide a
+lot of flexibility for managing DMs in your organization. For example, you can:
 
-    This feature is beta; see the notes below for details.
+- Prevent 1:1 DMs between [guest users](/help/guest-users).
+- Allow members to respond to DMs from an admin or moderator, but not to start
+  DM conversations.
+- Disable direct messages altogether.
+
+Regardless of how these settings are configured, users can always send direct messages
+to bots and to themselves.
+
+!!! tip ""
+
+    When restricting direct messages, consider also [restricting who can create
+    private channels](/help/configure-who-can-create-channels).
+
+## Configure who can authorize a direct message conversation
 
 {start_tabs}
 
 {settings_tab|organization-permissions}
 
-1. Under **Other permissions**, configure **Who can use direct messages**.
+1. Under **Direct message permissions**, configure **Who can authorize a direct
+   message conversation**.
 
 {!save-changes.md!}
 
 {end_tabs}
 
-### Notes on restricting direct messages
+## Configure who can start a direct message conversation
 
-* Disabling direct messages will cause sending a direct message to
-throw an error; the Zulip UI will appear to still allow direct
-messages. We expect to make some UI adjustments when direct messages
-are disabled during the beta period.
+{start_tabs}
 
-* Even if direct messages are disabled, users can still exchange
-direct messages with bot users (this detail is important for
-Zulip's new user onboarding experience). Consider also [restricting
-bot creation](/help/restrict-bot-creation) when using this feature.
+{settings_tab|organization-permissions}
 
-* Restricting direct messages does not automatically [restrict creating
-private channels](/help/configure-who-can-create-channels).
+1. Under **Direct message permissions**, configure **Who can start a direct
+   message conversation**.
+
+{!save-changes.md!}
+
+{end_tabs}
+
+## Disable direct messages
+
+{start_tabs}
+
+{settings_tab|organization-permissions}
+
+1. Under **Direct message permissions**, set **Who can authorize a direct
+   message conversation** to **Direct messages disabled**.
+
+{!save-changes.md!}
+
+{end_tabs}
+
+## Related articles
+
+* [Direct messages](/help/direct-messages)
+* [Restrict channel creation](/help/configure-who-can-create-channels)