Old versions of operating systems tended to be shipped with old
. Old versions should be replaced because
they are insecure.
Current versions of operating systems tend to ship with V8.7
sendmail. To find out which version you are running, issue the following
/usr/lib/sendmail -d0.1 -bt < /dev/null
The first line (of possibly many) printed should contain the version
If no version is displayed, you may be running a very old version
indeed, or some other program masquerading as
In either instance, you should upgrade.
If version 8.6.13 or earlier is displayed,
you should also plan to upgrade.
If version 8.7.5 or earlier is displayed, you should also plan to upgrade.
Version 8.7.6 was the last (as of this writing) secure version of the 8.7 series.
A more difficult decision is whether or not to upgrade if you are already
. Potential reasons for upgrading are the following:
program has always been a prime target of attack
by crackers (probably because it is distributed as source code). One
reason to always run the latest version of
earlier versions may have been compromised. Even if your current version
is secure, a C library may not be. If you have been notified of
a security hole in your library, you should consider recompiling
, using a new, secure library.
After widespread use and abuse, any program will begin to show
its bugs. The
program, although superbly written,
is no exception. One reason new versions are periodically released
is to fix reported bugs. At the very least, download the latest
source and look at the release notes to see whether a bug may be biting
At a heterogeneous site (as most sites are these days) it is often
more convenient to run a common version of
configuration files. Only by compiling and installing from the source
can you achieve a controllable level of uniformity.
A precompiled version of
may lack certain features
that you find desirable, or it may have features that you would prefer
Section 18.8, "Alphabetized Reference"
lists the debugging
switches that you can use to determine what kind of features your
has available. If debugging switches are unavailable, the
individual sections at the end of this chapter discuss other
methods to determine feature support or the lack of it.
But beware: Before rushing out and replacing your vendor's version of
, find out whether it uses any special vendor-specific
features. If so, and if those features are more valuable to you than
the security and uniformity that we mentioned, convince your vendor to
upgrade for you.