delivery errors?

[Samuel Dries-Daffner]

Any ideas what cause these types of errors?

from maillog:

Mar 17 07:31:09 1C:ella ipop3d[1417154]: Retrying after disk error
user=spertus host=UNKNOWN mbx=/acct/faculty/spertus/mbox: Invalid argument


from syslog.critical

Mar 16 23:57:57 1C:ella ipop3d[1417154]: Retrying after disk error
user=spertus host=206.111.145.243 mbx=/acct/faculty/spertus/mbox: Error 0