Due to a bot/spam attack on hyperreal.org, and Brian B's countermeasures, many popular Brazilian mail servers were temporarily blacklisted for outgoing e-mail.
Unfortunately, this meant that at least one and potentially several people in Brazil were booted off 313 because their mail was bouncing. I've sorted out Guilherme Arrantes, if you know of anyone else that ran into this problem, tell them it's OK to re-subscribe now.