specifies whether to allow interaction with channels that contain functions that might be executed in your session in response to events on the channel.


  • By default, $AllowExternalChannelFunctions is False and has attribute Protected.
  • Using $AllowExternalChannelFunctions=True can create a significant security risk, because it allows code specified by the creator of a channel to automatically be executed whenever you listen or send to that channel.
  • $AllowExternalChannelFunctions can also be reset from the Security tab in the Preferences dialog in the notebook interface.


Basic Examples  (1)

Try to send a message on another user's channel with the default security settings in place:

Enable communication on other users' channels:

Now it is possible to send messages to another user's channel:

Restore security settings:

Introduced in 2016
Updated in 2020