Enter the channel names or user ids to which notifications should be sent. Note that this can include names of channels OR channel id numbers, e.g. "#builds", and that multiple values may appear comma separated. While names are more readable, channel ids will not change over time and are therefore more resilient.
Thread support is available for slack APPs that handle requests using "chat.postMessage" method. Besides to the channel ID, thread_ts must be passed to the SlackRoom parameter, separated by a colon (:).
Ex: ABCD1234S:1528273109
"chat.postMessage" endpoint could not handle `names of channels`, `channel id numbers` need to be used.
This overrides the global setting.