Recipe error

I have a lengthy spam filter recipe installed on my system.  For some
users, I get a error such as:

procmail: Error while writing to " $FORMAIL -A"X-SpamBouncer: Bulk" \
        -A"X-SpamRule: FROM_DAEMON" >>$BULKFOLDER"

This error does not occur for some other users.  I have yet to
see a correlation between the error and some other factor, such
as the users's shell, for instance.

Any help is appreciated

Suresh