I have several subscribers to mailing lists on my site who use earthlink/mindspring as their internet provider. Earthlink apparently treats any 451 error as a permanent error by having a 0 retry time. Obviously, I don't want to whitelist all of their netblock. Has anyone attempted to talk to them how bad it is to reject mail sent by subscribers without a retry? And does anyone have a list of the mail servers from which mail may be forwarded from earthlink/mindspring?
Message
Earthlink treats 4xx as 5xx errors
2007-09-12 by California_Condor