diff --git a/addons/im_livechat/static/src/models/messaging_initializer/messaging_initializer.js b/addons/im_livechat/static/src/models/messaging_initializer/messaging_initializer.js
index 4780cf041a4..6a98302e668 100644
--- a/addons/im_livechat/static/src/models/messaging_initializer/messaging_initializer.js
+++ b/addons/im_livechat/static/src/models/messaging_initializer/messaging_initializer.js
@@ -20,9 +20,14 @@ registerInstancePatchModel('mail.messaging_initializer', 'im_livechat/static/src
             // there might be a lot of channels, insert each of them one by
             // one asynchronously to avoid blocking the UI
             await this.async(() => new Promise(resolve => setTimeout(resolve)));
-            this.env.models['mail.thread'].insert(
+            const channel = this.env.models['mail.thread'].insert(
                 this.env.models['mail.thread'].convertData(data),
             );
+            // flux specific: channels received at init have to be
+            // considered pinned. task-2284357
+            if (!channel.isPinned) {
+                channel.update({ isPendingPinned: true });
+            }
         }
     },
 });
diff --git a/addons/mail/static/src/models/messaging_initializer/messaging_initializer.js b/addons/mail/static/src/models/messaging_initializer/messaging_initializer.js
index b258e5502a3..6272baf9c84 100644
--- a/addons/mail/static/src/models/messaging_initializer/messaging_initializer.js
+++ b/addons/mail/static/src/models/messaging_initializer/messaging_initializer.js
@@ -153,9 +153,14 @@ function factory(dependencies) {
                 // there might be a lot of channels, insert each of them one by
                 // one asynchronously to avoid blocking the UI
                 await this.async(() => new Promise(resolve => setTimeout(resolve)));
-                this.env.models['mail.thread'].insert(
+                const channel = this.env.models['mail.thread'].insert(
                     this.env.models['mail.thread'].convertData(channelData)
                 );
+                // flux specific: channels received at init have to be
+                // considered pinned. task-2284357
+                if (!channel.isPinned) {
+                    channel.update({ isPendingPinned: true });
+                }
             }
         }
 
diff --git a/addons/mail/static/src/models/thread/thread.js b/addons/mail/static/src/models/thread/thread.js
index 837de254d9d..cfc0672df93 100644
--- a/addons/mail/static/src/models/thread/thread.js
+++ b/addons/mail/static/src/models/thread/thread.js
@@ -164,13 +164,6 @@ function factory(dependencies) {
             }
             if ('is_pinned' in data) {
                 data2.isServerPinned = data.is_pinned;
-                // FIXME: The following is admittedly odd.
-                // Fixing it should entail a deeper reflexion on the group_based_subscription
-                // and is_pinned functionalities, especially in python.
-                // task-2284357
-                if ('group_based_subscription' in data && data.group_based_subscription) {
-                    data2.isServerPinned = true;
-                }
             }
             if ('last_message' in data && data.last_message) {
                 data2.messagesAsServerChannel.push(['insert', { id: data.last_message.id }]);