If you run sendmail from the Debian (Etch) packages and you use FEATURE(`smrsh’) then you must put the symlinks of the commands that you want smrsh to execute under /etc/mail/smrsh and not under /usr/lib/sm.bin . The Debian manpage is not particularly helpful on this.
From sendmail’s configuration README:
smrsh Use the SendMail Restricted SHell (smrsh) provided with the distribution instead of /bin/sh for mailing to programs. This improves the ability of the local system administrator to control what gets run via e-mail. If an argument is provided it is used as the pathname to smrsh; otherwise, the path defined by confEBINDIR is used for the smrsh binary -- by default, /usr/libexec/smrsh is assumed.