At least 1 user needs to be subscribed to a magazine in order for it to receive federated updates, so keep that in mind after searching for a new magazine/community. I get subscribed to everything by default (hopefully Mbin will change this behavior in the future), so if it’s not a magazine I want to see in my feed I will unsubscribe. :-)

EDIT: i’ve pushed a code change to Mbin so that the admin user is no longer auto-subscribed to new federated magazine searches. https://github.com/MbinOrg/mbin/pull/237