Hi,
It works from the command line? that's kind of surprising. It may work via tab completion in the shell, but will not work with that as typed. You'd suffer from shell expansion.
# clean up postmaster 00 30 * * * root /usr/bin/find /var/qmail/maildirs/postmaster@telbit.pt/Maildir/new -type f -print0 | xargs -0 -n 50 rm
Of course that in the command shell i only run: $ /usr/bin/find /var/qmail/maildirs/postmaster@telbit.pt/Maildir/new -type f -print0 | xargs -0 -n 50 rm
Warm Regards, Mário Gamito