Hi guys,
My shrinking brain is experiencing a misunderstanding of
the DNS TRY_AGAIN response and delivery deferral. A specific
example I found recently involves messages addressed to
the domain "iwasborn.com"
Here is a short portion of debugging output from exim-4.10 for
a message addressed to iwasborn.com:
routing nobody@???
--------> lookuphost router <--------
local_part=nobody domain=iwasborn.com
checking domains
iwasborn.com in "mail.engr.ucsb.edu : engineering.ucsb.edu : engr.ucsb.edu : alumni.engr.ucsb.edu : eci.ucsb.edu : cnsi.ucsb.edu
: www1.engr.ucsb.edu"? no (end of list)
iwasborn.com in "! +local_domains"? yes (end of list)
cached lookup data = NULL
calling lookuphost router
lookuphost router called for nobody@???
domain = iwasborn.com
DNS lookup of iwasborn.com (MX) gave TRY_AGAIN
iwasborn.com in dns_again_means_nonexist? no (option unset)
returning DNS_AGAIN
lookuphost router: defer for nobody@???
message: host lookup did not complete
nobody@??? cannot be resolved at this time:
host lookup did not complete
search_tidyup called
>>>>>>>>>>>>>>>>>> Exim pid=21147 terminating with rc=1 >>>>>>>>>>>>>>>>>>
I would have thought this would still queue the message for delivery
and try again later (although I have a feeling iwasborn.com
will never be back, other domains returning TRY_AGAIN might
only be unavailable temporarily); however, the message is rejected
immediately with a 451 error after the rcpt:
[root@mail]# telnet mail.engr.ucsb.edu 25
Trying 127.0.0.1...
Connected to mail.engr.ucsb.edu.
Escape character is '^]'.
220-mail.engr.ucsb.edu ESMTP Exim 4.10 2 Wed, 23 Oct 2002 09:19:22 -0700
220- This equipment is located in California. In accordance with 17538.45
220- of the California Business and Professional Code, unsolicited
220- electronic mail advertisements are prohibited. See
220 http://www.engr.ucsb.edu/eci/UEMA_policy.html for details.
helo engr.ucsb.edu
250 mail.engr.ucsb.edu Hello root at mail.engr.ucsb.edu [127.0.0.1]
mail from: nobody@???
250 OK
rcpt to: nobody@???
451 Temporary local problem - please try later
I don't have any recipient verification enabled in the ACLs.
My hope would be that the message could be accepted and queued for
further delivery attempts, and then eventually bounced if their
DNS continued to return TRY_AGAIN.
Am I missing something obvious here?
Thanks!
Tom
