[Mailman-Users] Ongoing delivery issues - First Yahoo, now AOL

Mark Sapiro mark at msapiro.net
Sat Mar 8 17:33:45 CET 2008

Matt Morgan wrote:

>On Fri, Mar 7, 2008 at 2:58 PM, Mark Sapiro <mark at msapiro.net> wrote:
>>  Since your original post on this issue, I have looked at my maillog and
>>  I see lots of these
>>  host e.mx.mail.yahoo.com[] refused to talk to me: 421 4.7.0
>>  [TS01] Messages from temporarily deferred due to user
>>  complaints -; see http://postmaster.yahoo.com/421-ts01.html
>>  type messages (3500 in the last month, but only 46 in the last 5 days).
>>  I also get lots of
>>  host g.mx.mail.yahoo.com[] said: 451 Message temporarily
>>  deferred - [250] (in reply to end of DATA command)
>>  and
>>  host c.mx.mail.yahoo.com[] said: 421 Message temporarily
>>  deferred - 4.16.51. Please refer to
>>  http://help.yahoo.com/help/us/mail/defer/defer-06.html (in reply to
>>  end of DATA command)
>>  and
>>  host c.mx.mail.yahoo.com[] refused to talk to me: 421
>>  Message temporarily deferred - Please refer to
>>  http://help.yahoo.com/help/us/mail/defer/defer-06.html
>This is greylisting:

This was discussed last month in the thread at

The first and fourth deferrals above are definitely not greylisting as
I know it as they come in response to the connect before the server
knows either the sender or the recipient. Even if they are
'greylisting' at the IP level, by now all the Yahoo MXs should have
identified my IP as one that retries, yet I still see these deferrals.

The second and third deferrals could be greylisting, except they are
not very effective greylisting in that they occur seemingly at random
in that a message with a specific sender and recipient will often be
accepted and then a later message with the same sender and recipient
will be deferred by the same MX.

Also, the discussions on the Yahoo pages in the status messages are not
consistent with greylisting per se.

Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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