It's too late for this case, but maybe a group message telling that sig-arm was being shut down and that users should manually join the Embedded group would have been useful for those not following ros-users too.
Otherwise one could just try to post or reply to a message, and get the delivery system tell him the group doesn't exist.

Now since I follow this too I know, but maybe others don't.

Maybe next time.
Regards

Eng. Claudio Carbone
Embedded Systems Design

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