Mail Server Problem

Hi All,
I am having a problem with my mail server. This server has Sun OS on which
is run exim 4.10, courrier imap and webmail. The problem is that clients
complain about they not being able to receive their mails even though their
quota is not exhausted and the /home directory is not full. This is the
message I found in my mailbox:

This message was created automatically by mail delivery software (Exim).
A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:
mensahk at ghana.com
local delivery failed
The following text was generated during the delivery attempt:
------ mensahk at ghana.com ------
/home/mensahk/Maildir/tmp/1040709379.24189.hostname: No space left on device

And in /var/spool/exim/log/paniclog
#tail paniclog
2002-11-29 15:38:50 queue run: process 25854 crashed with signal 11 while
delivering 18HmT1-0002XV-00
2002-11-29 15:53:50 queue run: process 766 crashed with signal 11 while
delivering 18HmT1-0002XV-00
2002-11-29 16:08:51 queue run: process 6297 crashed with signal 11 while
delivering 18HmT1-0002XV-00
2002-11-29 16:23:50 queue run: process 11434 crashed with signal 11 while
delivering 18HmT1-0002XV-00
2002-11-29 16:50:26 queue run: process 20297 crashed with signal 11 while
delivering 18HmT1-0002XV-00
2002-11-29 16:53:46 queue run: process 21977 crashed with signal 11 while
delivering 18HmT1-0002XV-00
2002-11-29 17:23:58 queue run: process 867 crashed with signal 11 while
delivering 18HmT1-0002XV-00
2002-11-29 17:27:51 queue run: process 3380 crashed with signal 11 while
delivering 18HmT1-0002XV-00
2002-11-29 17:38:46 queue run: process 7152 crashed with signal 11 while
delivering 18HmT1-0002XV-00
2002-11-29 17:53:45 queue run: process 12775 crashed with signal 11 while
delivering 18HmT1-0002XV-00
#

# df -k
Filesystem            kbytes    used   avail capacity Mounted on
/dev/dsk/c0t0d0s0    8261393 313881 7864899     4%    /
/dev/dsk/c0t0d0s3    7131445 2431154 4628977    35%    /usr
/proc                      0       0       0     0%    /proc
fd                         0       0       0     0%    /dev/fd
mnttab                     0       0       0     0%    /etc/mnttab
/dev/dsk/c0t8d0s7    17413250 1129923 16109195     7%    /var
swap                 1508760      32 1508728     1%    /var/run
swap                 1509048     320 1508728     1%    /tmp
/dev/dsk/c0t9d0s7    17413250 13392517 3846601    78%    /home
/dev/dsk/c0t0d0s7     941235       9 884752     1%    /export/home
#