We figured out the e-mail issue -- the IP address of the temporary server we are using (hosted by Rackspace.com) was on a spam blacklist. Rackspace has helped us take the IP off the blacklist. Some organizations, however, have a delay before they recognize an IP again.

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Update: we are now routing outgoing mail through our Google mail service (the infrastructure that provides @neopoet.com e-mail for site administrators). This appears to be resolved.