Since upgrading from 4.5 to 4.6-*, I have had problems exchanging
email with a correspondent at "austinenergy.com". It shows up as:
% echo hi | mail -v [EMAIL PROTECTED]
austinenergy.com: Name server timeout
[EMAIL PROTECTED] Transient parse error -- message queued for
future delivery
[EMAIL PROTECTED] queued
I have tracked this down to the fact that sendmail is using a IPv6-style
lookup request. It is a "AAAA ?" rather than a "A ?" (in tcpdump-esque).
Further investigation dug up this manifesto in the sendmail README:
When attempting to canonify a hostname, some broken name
servers will return SERVFAIL (a temporary failure) on T_AAAA
(IPv6) lookups. If you want to excuse this behavior, include
WorkAroundBrokenAAAA in ResolverOptions. However, instead,
we recommend catching the problem and reporting it to the
name server administrator so we can rid the world of broken
name servers.
So, in violation of the networking "be liberal in what you accept and
conservative in what you produce", sendmail in it's new form will have many
perplexed sysadmins spending lots of time tracking down these mysterious
failures.
I suggest that the version of sendmail configs shipped with FreeBSD
should default to having WorkAroundBrokenAAAA set by default.
--
--
Damon Permezel
[EMAIL PROTECTED]
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