Our DNS issues have been resolved, meaning that if you're in the habit of going to http://feedmeshow.com (vs. http://feedmeshow.ning.com), it'll work for you again. Thanks, DynDNS!
No DNS solution possible, according to the great people at dyndns, who have for years delivered the best tech support of any organization I've dealt with, but Rauch helped me work out a Postfix hack that might do the job.