interesting lockup with Slackware current

[Doug Sutherland]

Sendmail ... "locking up" ... are you sure its not timing out.
This is a common problem. Try letting it sit for a few minutes
and see if sendmail times out and the boot sequence proceeds.

One thing you can try is changing the permissions on the sendmail
startup run control file /etc/rc.d/rc.sendmail. If its send to
not execute (chmod -x) then slackware won't start sendmail.

But that's probably not what you want :)
This problem (sendmail delay) is sometimes due to there being
no localhost defined in the /etc/hosts file. Check yours and
make sure you have in there:

127.0.0.1 localhost

   -- Doug