Qpopper 4.0 cross-device link?

[Forrest Aldrich]

I'm seeing this error with on of our pop accounts:

Apr 13 01:20:03 drama popper[50937]: Unable to move 
/var/spool/pop/.username.pop to /var/mail/username: Cross-device link (18)

I set up /var/spool/pop to be the --enable-temp-drop-dir option.   I'm not 
sure why this is happening for only this user (that I can see thus far).

Help?