WARNING - WARNING - WARNING - WARNING - WARNING - WARNING

  qmail does not support dot-locking internally.

  You are in danger of losing mail if you re-configure
  qmail without understanding the implications of this.

WARNING - WARNING - WARNING - WARNING - WARNING - WARNING

On Debian the standard location for a users mailbox is

  /var/spool/mail/<username>

and when programs write to that file they are expected to lock the
file to prevent another process from accessing it at the same time, and
thus corrupting your mail file.

For reasons explained in /usr/doc/qmail/INSTALL.mbox, qmail does not do this.

The default setup uses /usr/sbin/qmail-procmail to perform the final
delivery of mail with apropriate dot-locking to prevent loss of mail.
This is just a script that invokes procmail.

You should not really need to invoke this as a user, but if you can
think of a reason to do so, a line like this in your .qmail file will
result in normal delivery via procmail:

  |/usr/sbin/qmail-procmail

If you were to instead put something like:

  /var/spool/mail/phil

in your .qmail file, it would deliver mail to that file, but would
lock it using flock's rather than dot-lock's.  Unless you know
different, that would probably mean that every other program on the
system would consider the file to be unlocked, and would leave you
open to mail loss.

Personally, I'd recommend moving to Maildir/ format if you can.  Read
the files in /usr/doc/qmail to find out more.

---

How the Debian setup differs from standard qmail setups:

  The default setup sets aliasempty (i.e. the default delivery method)
  to be /usr/sbin/qmail-procmail, which is a wrapper around procmail.

  This results in delivery into /var/spool/mail.

  To change this to one of the more standard qmail setups edit
  /etc/init.d/qmail

  The binaries normail found in /var/qmail/bin have been split between
  /usr/bin and /usr/sbin.

  The configuration files have been moved to /etc/qmail and the queue
  has been moved to /var/spool/qmail.

  Symbolic links have been placed in /var/qmail to make it look like a
  normal qmail setup.

Phil Hands <phil@hands.com>