Here's how to set up the qmail groups and the qmail users.

On some systems there are commands that make this easy. Solaris:

   # groupadd nofiles
   # useradd -g nofiles -d /var/qmail/alias alias
   # useradd -g nofiles -d /var/qmail qmaild
   # useradd -g nofiles -d /var/qmail qmaill
   # useradd -g nofiles -d /var/qmail qmailp
   # groupadd qmail
   # useradd -g qmail -d /var/qmail qmailq
   # useradd -g qmail -d /var/qmail qmailr
   # useradd -g qmail -d /var/qmail qmails

BSDI 2.0:

   # addgroup nofiles
   # adduser -g nofiles -H/var/qmail/alias -G,,, -s/dev/null -P'*' alias
   # adduser -g nofiles -H/var/qmail -G,,, -s/dev/null -P'*' qmaild
   # adduser -g nofiles -H/var/qmail -G,,, -s/dev/null -P'*' qmaill
   # adduser -g nofiles -H/var/qmail -G,,, -s/dev/null -P'*' qmailp
   # addgroup qmail
   # adduser -g qmail -H/var/qmail -G,,, -s/dev/null -P'*' qmailq
   # adduser -g qmail -H/var/qmail -G,,, -s/dev/null -P'*' qmailr
   # adduser -g qmail -H/var/qmail -G,,, -s/dev/null -P'*' qmails

AIX:

   # mkgroup -A nofiles
   # mkuser pgrp=nofiles home=/var/qmail/alias shell=/bin/true alias
   # mkuser pgrp=nofiles home=/var/qmail shell=/bin/true qmaild
   # mkuser pgrp=nofiles home=/var/qmail shell=/bin/true qmaill
   # mkuser pgrp=nofiles home=/var/qmail shell=/bin/true qmailp
   # mkgroup -A qmail
   # mkuser pgrp=qmail home=/var/qmail shell=/bin/true qmailq
   # mkuser pgrp=qmail home=/var/qmail shell=/bin/true qmailr
   # mkuser pgrp=qmail home=/var/qmail shell=/bin/true qmails

On other systems, you will have to edit /etc/group and /etc/passwd
manually. First add two new lines to /etc/group, something like

        qmail:*:2107:
        nofiles:*:2108:

where 2107 and 2108 are different from the other gids in /etc/group.
Next (using vipw) add six new lines to /etc/passwd, something like

        alias:*:7790:2108::/var/qmail/alias:/bin/true
        qmaild:*:7791:2108::/var/qmail:/bin/true
        qmaill:*:7792:2108::/var/qmail:/bin/true
        qmailp:*:7793:2108::/var/qmail:/bin/true
        qmailq:*:7794:2107::/var/qmail:/bin/true
        qmailr:*:7795:2107::/var/qmail:/bin/true
        qmails:*:7796:2107::/var/qmail:/bin/true

where 7790 through 7796 are _new_ uids, 2107 is the qmail gid, and 2108
is the nofiles gid. Make sure you use the nofiles gid for qmaild,
qmaill, qmailp, and alias, and the qmail gid for qmailq, qmailr, and
qmails.