At times, such as when calling /bin/mail to
deliver local mail, sendmail holds an entire
message internally while waiting for that delivery to complete.
Clearly, this runs the risk that the message will be lost if the
system crashes at the wrong time.
As a safeguard against such rare catastrophes, the
SuperSafe option can be used to force
sendmail to queue every message and to
sync(2) the queued files to disk for maximum
safety. The queued copy is left in place until
sendmail is sure that delivery was successful.
We strongly recommend that this option always be declared as true.
The forms of the SuperSafe option are as follows:
O SuperSafe=character configuration file (V8.12 and later)
-OSuperSafe=character command line (V8.12 and later)
define(`confSAFE_QUEUE',`character') mc configuration (V8.12 and later)
O SuperSafe=bool configuration file (V8.7 and later)
-OSuperSafe=bool command line (V8.7 and later)
define(`confSAFE_QUEUE',`bool') mc configuration (V8.7 and later)
Osbool configuration file (deprecated)
-osbool command line (deprecated)
The argument, prior to V8.12, was of type
Boolean. The argument, with V8.12 and later, is
of type Character. If the argument is missing,
the default value is true (everything is queued). The default for the
mc configuration technique is also true. If the
entire SuperSafe option is missing, the default
for V8.11 and earlier becomes false (no special queuing behavior),
but for V8.12 and later it becomes true (everything is queued).
Beginning with V8.12, a third alternative to true or false was
introduced that is useful with
sendmail's interactive delivery
mode, and is called i for
interactive. For example:
define(`confSAFE_QUEUE', `interactive') V8.12 and later
This interactive setting for the
SuperSafe option causes
sendmail to skip unneeded secondary
At high-volume sites that perhaps send subscription email, there can
be benefit (and increased risk) to turning off this
SuperSafe option (see also Section 6.4):
define(`confSAFE_QUEUE', `false') strongly discouraged
The SuperSafe option is safe. Even if it is
specified from the command line, sendmail
retains its special privileges.