When a team with a contact address is subscribed to a branch, and that contact address is an external mailing list, the branch notification email has an unhelpful footer.
Specifically, the text to unsubscribe from the branch is misleading and confusing:
To unsubscribe from this branch go to https://code.launchpad.net/~mailman-coders/mailman/2.1/+subscription/mailman-checkins
The problem with this is that this subscription url is for the team whose only purpose is to provide a contact address to send branch diffs to <email address hidden>. Ordinary recipients of the diff message (rightly) can't unsubscribe the team from that branch, but they also aren't told they can unsubscribe themselves by going to the mailing list.
It should be possible for a team to set a specific external unsubscription url when they have a contact address. That way I, as owner of the mailman-checkins team could point this url at the standard mailman-checkins mailing list unsubscribe page.
Very good suggestion.