[jamesloker]

I have had webmin installed with the postfix module since before this happened.
No updates for at least a couple of weeks and have restarted since then.
Loads of space
df -h returns this

root@belle:/var/vmail/glemsfordschool.local# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda1             224G  5.8G  207G   3% /
tmpfs                 993M     0  993M   0% /lib/init/rw
varrun                993M  380K  993M   1% /var/run
varlock               993M     0  993M   0% /var/lock
udev                  993M  140K  993M   1% /dev
tmpfs                 993M     0  993M   0% /dev/shm
lrm                   993M  2.5M  991M   1% /lib/modules/2.6.28-17-server/volatile
root@belle:/var/vmail/glemsfordschool.local#

So lots there.