At 11:17 04/07/2000 Friday , Angus wrote:
 >A listowner friend.. got the following from the postmaster of a
 >subscriber's server after she asked them to look into why her subscriber
 >kept getting deleted from the list due to:
 >
 >> >> - The  last reported  error was:  Mailer mail12.SKYWIZARD.COM
 >> >> said: "551 <[log in to unmask]>... we do not relay"
 >
 >errors.  The listowner got the following back.. and suggestions on what to
 >tell this provider?

My guess is that the postmaster is incorrect and that one or more (but not ALL) of the Mail Exchangers is either misconfigured or should not be included in the list of MX hosts:

Query:Mail Exchange (MX):SKYWIZARD.COM
SKYWIZARD.COM   MX      100     mail11.SKYWIZARD.COM
SKYWIZARD.COM   MX      80      mail12.SKYWIZARD.COM
SKYWIZARD.COM   MX      10      mail.SKYWIZARD.COM
SKYWIZARD.COM   NS      radius2.SKYWIZARD.COM
SKYWIZARD.COM   NS      ns.skywizard1.net
SKYWIZARD.COM   NS      ns3.ctel.net
SKYWIZARD.COM   NS      ns1.ctel.net
SKYWIZARD.COM   NS      radius1.SKYWIZARD.COM
mail11.SKYWIZARD.COM    A       209.222.84.11
mail12.SKYWIZARD.COM    A       209.222.84.12
mail.SKYWIZARD.COM      A       207.41.39.12
radius2.SKYWIZARD.COM   A       209.222.84.12
ns.skywizard1.net       A       209.222.84.12
ns1.ctel.net    A       209.222.72.3
radius1.SKYWIZARD.COM   A       209.222.84.11
Complete: SKYWIZARD.COM

Note that report MTA was mail12.SKYWIZARD.COM which is NOT the most preferred MX record.  If you are using Eudora (or some  other configurable MTA) you could probably verify the reliability of your personal email to the subscriber by using each MX host, in turn, to deliver a test message.

That techique has served me well for those mal-administered DNS/MTAs for other sites.  Sometimes it takes four months, and several progressive nasty-grams to convince folks.  And those sites aren't necessarily small potateoes either!

YMMV.

/Pete Weiss
Sr. Systems Engineer -- Penn State