-T
Suffix to append on temporary failure V8.10 and later
When a resource is temporarily unavailable, it would be handy if sendmail indicated that unavailability when the database lookup fails. Consider NIS, for example. It can time out when a server is down briefly, but a failed lookup of a user’s login name need not cause a permanent failure under such a circumstance. Instead, something should be returned to show that it is only a temporary failure.
The -T
database
switch was added with V8.10
sendmail to solve this
problem. You use it to define a suffix to add to the
key for the returned failure value when the problem
is temporary. You might use it like this:
Kmailservers nis -T.Defer -o mailservers ... R $* <@ $+ > $* $: $1<@$2>$3 <$(mailservers $2 $: Fail $)> R $* <@ $+ > $* <$* . Defer> $# error $@ 4.2.2 $: "450 defer" ← handle failure here R $* <@ $+ > $* <Fail> $# error $@ 5.7.1 $: "550 reject" ← handle failure here R $* <@ $+ > $* <$+> $# smtp $@ $4 $: $1 < @ $2 > $3 ← OK, so send it ...
Note that a permanent failure returns the failure
alternative indicated by the $
: operator (the
Fail
). But a
temporary failure returns the suffix defined by the
-T
, appended to
the original key (the $2
) to form $2.Defer
.
Note that this definition of temporary failure is
different from that defined by the -D
database switch. With
-D
, database
lookups are not done at all if the DeliveryMode
option
(DeliveryMode on page 1004) is
set to defer
.
Also note that this -T
database switch affects only the ...
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