diff --git a/lib/stream-chat/client.rb b/lib/stream-chat/client.rb
index dbbd7ab..13a96f1 100644
--- a/lib/stream-chat/client.rb
+++ b/lib/stream-chat/client.rb
@@ -1065,6 +1065,15 @@ def query_reminders(user_id, filter_conditions = {}, sort: nil, **options)
       post('reminders/query', data: params)
     end
 
+    # Send the mark delivered event for this user, only works if the `delivery_receipts` setting is enabled
+    #
+    # @param [StringKeyHash, nil] data The delivery confirmation data
+    # @return [StreamChat::StreamResponse] API response
+    sig { params(data: T.nilable(StringKeyHash), user_id: T.nilable(String)).returns(StreamChat::StreamResponse) }
+    def mark_delivered(data = nil, user_id: nil)
+      post('channels/delivered', data: data || {}, params: { user_id: user_id })
+    end
+
     private
 
     sig { returns(T::Hash[String, String]) }
diff --git a/spec/channel_spec.rb b/spec/channel_spec.rb
index 9ff2755..0971ef3 100644
--- a/spec/channel_spec.rb
+++ b/spec/channel_spec.rb
@@ -354,6 +354,9 @@ def loop_times(times)
   end
 
   it 'can send message with restricted visibility' do
+    # Add users as members before testing restricted visibility
+    @channel.add_members([@random_users[0][:id], @random_users[1][:id]])
+
     # Send a message that's only visible to specific users
     msg = @channel.send_message(
       {
@@ -372,6 +375,9 @@ def loop_times(times)
   end
 
   it 'can update message with restricted visibility' do
+    # Add users as members before testing restricted visibility
+    @channel.add_members([@random_users[0][:id], @random_users[1][:id]])
+
     # First send a regular message
     msg = @channel.send_message(
       {
@@ -399,6 +405,9 @@ def loop_times(times)
   end
 
   it 'can update message partially with restricted visibility' do
+    # Add users as members before testing restricted visibility
+    @channel.add_members([@random_users[0][:id], @random_users[1][:id]])
+
     # First send a regular message
     msg = @channel.send_message(
       {
diff --git a/spec/client_spec.rb b/spec/client_spec.rb
index ddde19e..5dc819d 100644
--- a/spec/client_spec.rb
+++ b/spec/client_spec.rb
@@ -1435,4 +1435,28 @@ def loop_times(times)
       expect(response['active_live_locations'].length).to be >= 1
     end
   end
+
+  describe '#mark_delivered' do
+    it 'should mark messages as delivered' do
+      # Create some test messages first
+      message = @channel.send_message({ text: 'Test message 1' }, @frodo)
+
+      # Create delivery confirmation data
+      delivery_data = {
+        latest_delivered_messages: [
+          {
+            cid: @channel.cid,
+            id: message['message']['id']
+          }
+        ],
+        user_id: @gandalf
+      }
+
+      # Call the method
+      response = @client.mark_delivered(delivery_data, user_id: @gandalf)
+
+      # The response should be successful (status 201)
+      expect(response.status_code).to eq(201)
+    end
+  end
 end