Problems with /var partition filling up all the time [Linux Red Hat 7.3]

I am having a huge problem here with my /var partition filling up on my Linux Red Hat box. This is stopping all email sent from my web server due to lack of space. I usually solve the problem by deleting log files and other miscelaneous stuff on the /var directory but this time I ran out of files to delete.
So I was investigating and it seems like /var/lib/rpm is taking up a lot of space (26 MB) that I could use. Can I just delete this directory? Why is it so big??? I don't understand.
[root@internal var]# pwd
/var
[root@internal var]# du -sh *
41k     arpwatch
1.9M    cache
1.0k    db
2.0k    gdm
26M     lib
1.0k    local
2.0k    lock
3.2M    log
12k     lost+found
0       mail
1.0k    nis
1.0k    opt
1.0k    preserve
25k     run
29k     spool
1.0k    tmp
1.0k    tux
7.0k    webmin
1.1M    www
20k     yp
[root@internal var]#

As you can see the only thing there taking up a lot of space is lib which insisde contains RPM files which are taking a lot of space. Can I go ahead and delete those files or just empty whatever is in them.


Also notice that when I do : df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/hda6             372M  142M  211M  41% /
/dev/hda1              45M   18M   25M  42% /boot
/dev/hda5              11G  3.1G  7.3G  30% /home
none                  314M     0  313M   0% /dev/shm
/dev/hda2              24G  1.2G   21G   5% /usr
/dev/hda7             251M  238M     0 100% /var

/var seems to have 251 MB of space but when I do

[root@internal /]# du -sh *
5.8M    bin
14M     boot
270k    dev
5.9M    etc
3.1G    home
1.0k    initrd
92M     lib
12k     lost+found
1.0k    misc
3.0k    mnt
1.0k    opt
du: `proc/16060/fd/3': No such file or directory
2.0k    proc
4.7M    root
8.5M    sbin
115k    tmp
1.1G    usr
32M     var

It says var only is using 32MB?
How can this be?

I am somwhat stumped and I need my web server to start sending emails asap.