Retrieve number of members who haven't received a message

You can retrieve the number of members who haven’t received a specific message in a group channel through the getUndeliveredMembers() method. When the value of 0 is returned, it means that the message has been successfully delivered to all members in the channel.

try {
  final count = groupChannel.getUndeliveredMembers(message).length;
} catch (e) {
  // Handle error.
}