Earthlink MX from *Earthlink* dynamic IPs blocked?

I'm trying to get my sister's MythTV DVR to send her a daily email with its recording schedule. Earthlink is apparently blocking the email because it's coming from a dynamic address -- even though that address *is an Earthlink cablemodem*. Is there anyone from Earthlink email ops around who can confirm that's actually the proper interpretation of your policy? Cheers, -- jra