Old BSD-based versions of Unix, such as
SunOS 4.0.x and BSD 4.3, used the signal(2) and
sigsetmask(2) calls to set and release signals.
Modern versions of Unix use the sigaction(2) and
sigprocmask(2) pair of routines. For all
currently supported systems, BSD_3 is already correctly defined in
the devtools/OS files or in
sendmail/conf.h. You should need to define BSD_3
if you are porting to a previously unsupported, old BSD-based system:
When porting to a new system, you can test with the preceding
confENVDEF statement and, if successful, put a
permanent porting entry into sendmail/conf.h.
New ports should be reported to
firstname.lastname@example.org so that they can be folded
into future releases.