From Bugzilla Helper:
User-Agent: Mozilla/5.0 Galeon/1.2.6 (X11; Linux i686; U;) Gecko/20020830

Description of problem:
If QUEUE get set to "" in /etc/sysconfig/sendmail (haven't 
investigating the significance of this, but at least it happened
on my system when migrating from 7.3), then invoking sm-slient
completely hangs the machine when booting.


Version-Release number of selected component (if applicable):


How reproducible:
Always

Steps to Reproduce:
1.Set QUEUE="" in /etc/sysconfig/sendmail
2.Reboot
3.Wait forever

Of course, replacing step to by "/etc/init.d/sendmail restart" is
the preferred way of debugging this!	

Actual Results:  Machine hangs

Expected Results:  Machine should not hang!

Additional info:

In /etc/rc.d/init.d/sendmail, the sm-client is started up like this:
The problem seem to come from this line:

daemon --check sm-client /usr/sbin/sendmail -L sm-msp-queue -Ac \
                                $([ -n "$QUEUE" ] && echo -q$QUEUE)

Now, if QUEUE="", then there will not be a -q command line option.
This means that sendmail has no option indicating that it should run
as a deamon. Instead, it believes it should do its default "send mail"
thing, writes the error "Recipient names must be specified" and starts
waiting for stdin. 

There is a similar thing [i.e.$([ -n "$QUEUE" ] && echo -q$QUEUE] in starting
sendmail proper a few lines earlier, but in this case it
works because there is also a "-bd" option that indicates that 
daemon mode should be used.

I have a patch that I will attach - not sure if it is the best or right way,
but do have a look.