This is qpsmtpd, a flexible SMTP daemon written in Perl. For source code and project details, see http://smtpd.develooper.com/ For help with qpsmtpd itself, see the qpsmtpd mailing list at http://smtpd.develooper.com/list.html (archives are available, check there first). If you skipped the qpsmtpd configuration step when installing the package for the first time, and need to repeat it, run 'dpkg-reconfigure qpsmtpd'. A few notes on Debian's packaging of qpsmtpd: 1. Startup Qpsmtpd does not start up automatically by default. It is intended to fit alongside a preexisting MTA, such as Exim, Qmail or Postfix, or to proxy for a remote SMTP server. As most Debian systems installed out-of-the-box include an MTA listening on all interfaces on the usual port (TCP port 25), qpsmtpd cannot generally start up until this is remedied. 2. Configuration If you're new to qpsmtpd, start by reading through the configuration files in /etc/qpsmtpd/. Much of qpsmtpd's functionality, including fairly basic things like mail delivery, is handled by plugins, so pay particular attention to /etc/qpsmtpd/plugins. You might also find the mailing list archives at http://smtpd.develooper.com/list.html helpful. 3. Delivery into a Local MTA 3.a. Exim If you haven't done any particular configuration of your mail system yet, you probably have Exim installed as your local MTA. The install scripts will detect this and attempt to configure things properly, but cannot reconfigure exim itself. To allow qpsmtpd to spool into Exim without having the sender addresses munged, you should edit your Exim configuration to add the 'qpsmtpd' user to the trusted_users list. For example: in /etc/exim4/exim4.conf.template: # uucp should be able to set envelope-from to arbitrary values trusted_users = uucp : smtpd or, if you use the directory tree config style, in /etc/exim4/conf.d/main/02_exim4-config_options: # trusted users can set envelope-from to arbitrary values .ifndef MAIN_TRUSTED_USERS MAIN_TRUSTED_USERS = uucp : smtpd .endif 3.b. Postfix If you select the postfix delivery method via debconf when installing or reconfiguring qpsmtpd, the install scripts will try to add qpsmtpd to the 'postdrop' group, so as to be able to open the Postfix local delivery socket (/var/spool/postfix/public/cleanup on a Debian system). While in a typical Debian install the postfix socket is itself world-accessible, it is in a directory accessible only to the postdrop group. If you manually configure qpsmtpd to spool into Postfix, instead of using debconf, you will need to make this adjustment manually, by running: useradd qpsmtpd postdrop Although this is the fastest-performing option and is as secure as qpsmtpd itself, if you don't wish to give qpsmtpd membership in the postdrop group you can alternately configure Postfix to listen on a loopback TCP socket and use the SMTP proxy delivery method instead. 4. forkserver vs tcpserver The standard 'qpsmtpd' startup script is not installed, as it depends upon Dan Bernstein's non-free tcpserver. Instead the package uses qpsmtpd-forkserver, which manages the TCP socket itself at a modest gain in performance. If you for some reason need the tcpserver binary, see the source to this package or download it from the URL above.