We've been hit by the spammers, please have mercy

Meanwhile our real public mail server is vulnerable because
it runs Netscape mail (netra runs solaris 2.4 until SunSoft
gets our copy of 2.5.1 application server off back order;

Solaris sendmail may be older, the latest one is 8.8.5:


Its sendmail.cf is slightly different from the stock Solaris.

If you don't have the time to build, you may get a 2.5.1
sendmail binary (note, it's risky to download binaries, no
guarantees implied or expressed etc. etc.) under:

  /usr/ucb/sum 37416 388 .../sendmail.8.8.5

CERT advisories on sendmail are under http://www.cert.org.