Opened 10 years ago

Closed 7 years ago

#2154 closed Bug/Something is broken (fixed)

e-mail from getting deferred by yahoo with message 4.16.50

Reported by: Daniel Kahn Gillmor Owned by: Jamie McClelland
Priority: Urgent Component: Tech
Keywords: smtp Cc:
Sensitive: no


SMTP connections to are getting 4.16.50 deferral notices. (i think this message code is yahoo-specific).

it would probably be good to get it de-listed, possibly by filling out their non-bulk mail delivery issues form.

This is actively causing delivery problems for at least one domain on the server, and it appears to have started at the beginning of May and gotten significantly worse starting around a week ago.

I used this command to count responses with this error code per day:

 (cat /var/log/mail.log{,.1} && zcat /var/log/mail.log*.gz) | awk '/4\.16\.50/{ printf("%s%02d\n",$1,$2) }' | sort | uniq -c

Change History (4)

comment:1 Changed 10 years ago by Daniel Kahn Gillmor

note: the messages do seem to be eventually delivered to yahoo after a greylisting-typical delay.

however, at least one yahoo recipient has informed me that he did not get the messages (it's unclear whether he looked in his spam/junk box)

comment:2 Changed 10 years ago by Jamie McClelland

Thanks for the report dkg.

I've just submitted the form for june - let's see what happens. We also have a related ticket #1812 - for our bulk mail servers which is waiting on the completion of a privacy policy.


comment:3 Changed 10 years ago by Jamie McClelland

I received the following from Yahoo (Thu, 21 May 2009 13:05:15 -0700). I'm not convinced it will make a difference though (we'll have to check in a few days to see if the numbers have gone down since receiving this).

Hello Jamie,

Thank you for writing to Yahoo! Mail.

Please note that if you are not the mail server administrator for the
mail server(s) affected, we encourage you to contact the administrator
so they can address the possible issues regarding mailings from the mail
server. We also appreciate your report as your input helps us to
identify ways to constantly maintain and improve our service. We
apologize for any inconvenience this has caused you.

If you notice any further difficulties when delivering to Yahoo! Mail
accounts, after waiting a reasonable amount of time, please let us know
by replying directly to this email. However please note the following:

If you are receiving the error code "421 Message from x.x.x.x
temporarily deferred" or "451 Message temporarily deferred - 4.16.50" in
your SMTP logs, this indicates that the message you attempted to send
was not accepted by Yahoo! Mail servers. It is not a permanent error;
your system will automatically re-try later. If, after attempting to
deliver to Yahoo! and receive the 4.16.50 error repeatedly and conform
to the best sending practices outlined in the following page, we
encourage you to apply for prioritized sending at the link below.

Recommended Best Practices:

Prioritized Delivery (Please note that this form can also be used by
senders whose mailings are being directed to the Bulk Folder):

If you are receiving a separate error than that above, please provide
the text of any error messages you may have received. Also, providing
the specific IP address of the mail server that experienced the delivery
issue will help us to troubleshoot the issue more efficiently.

For assistance with delivery issues to Yahoo! Mail, please visit:

We appreciate your patience while we work to improve and maintain our

Thank you again for contacting Yahoo! Mail. Your case number for this
issue is 60741134. Please reference it in all future communication about
this particular issue.



Yahoo! Customer Care

comment:4 Changed 7 years ago by Daniel Kahn Gillmor

Resolution: fixed
Status: newclosed

messages appear to be flowing freely from june to yahoo now, as can be seen by the output of:

grep 'to=<[^@]*>' /var/log/mail.log | less

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