Installing courier-mta causes sendmail to be installed instead

My Debian workstation will not install courier-mta. The command aptitude install courier-mta appears to complete without error, but actually installs sendmail instead. # What I did I'll start without any packages installed which provide mail-transfer-agent: dpkg --get-selections 'courier*' 'sendmail*' 'exim*' sensible-mda | awk '{print $1}' | xargs sudo dpkg --purge --force-depends ... root@treebeard:/etc/logcheck/violations.ignore.d$ dpkg -l 'courier*' 'sendmail*' 'exim*' sensible-mda Desired=Unknown/Install/Remove/Purge/Hold | Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend |/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad) ||/ Name Version Architecture Description +++-===============================================-============================-============================-=================================================================================================== un exim4 (no description available) dpkg-query: no packages found matching courier* dpkg-query: no packages found matching sendmail* dpkg-query: no packages found matching sensible-mda And then install courier-mta: root@treebeard:/etc/logcheck/violations.ignore.d$ sudo aptitude install courier-mta The following NEW packages will be installed: courier-authdaemon{a} courier-authlib{a} courier-authlib-userdb{a} courier-base{a} courier-mta 0 packages upgraded, 5 newly installed, 0 to remove and 0 not upgraded. Need to get 0 B/1,261 kB of archives. After unpacking 2,887 kB will be used. Do you want to continue? [Y/n/?] Preconfiguring packages ... Configuring courier-base ------------------------ Courier uses several configuration files in /etc/courier. Some of these files can be replaced by a subdirectory whose contents are concatenated and treated as a single, consolidated, configuration file. The web-based administration provided by the courier-webadmin package relies on configuration directories instead of configuration files. If you agree, any directories needed for the web-based administration tool will be created unless there is already a plain file in place. Create directories for web-based administration? no Configuring courier-mta ----------------------- Please specify a valid email domain. Most header rewriting functions will append this domain to all email addresses which do not specify a domain, such as local accounts. Default domain: fake.domain Please specify a valid value for the "From" header for mail delivery notifications. These notifications cannot be sent without that setting. "From" header for delivery notifications: noreply@fake.domain Selecting previously unselected package courier-authlib. (Reading database ... 249566 files and directories currently installed.) Unpacking courier-authlib (from .../courier-authlib_0.63.0-6+b1_i386.deb) ... Selecting previously unselected package courier-authdaemon. Unpacking courier-authdaemon (from .../courier-authdaemon_0.63.0-6+b1_i386.deb) ... Selecting previously unselected package courier-authlib-userdb. Unpacking courier-authlib-userdb (from .../courier-authlib-userdb_0.63.0-6+b1_i386.deb) ... Selecting previously unselected package courier-base. Unpacking courier-base (from .../courier-base_0.68.2-1_i386.deb) ... Selecting previously unselected package courier-mta. Unpacking courier-mta (from .../courier-mta_0.68.2-1_i386.deb) ... Adding 'diversion of /usr/bin/addcr to /usr/bin/addcr.ucspi-tcp by courier-mta' Adding 'diversion of /usr/share/man/man1/addcr.1.gz to /usr/share/man/man1/addcr.ucspi-tcp.1.gz by courier-mta' Processing triggers for man-db ... Setting up courier-authlib (0.63.0-6+b1) ... Setting up courier-authdaemon (0.63.0-6+b1) ... [ ok ] Starting Courier authentication services: authdaemond. Setting up courier-authlib-userdb (0.63.0-6+b1) ... Setting up courier-base (0.68.2-1) ... update-alternatives: using /usr/bin/deliverquota.courier to provide /usr/bin/deliverquota (deliverquota) in auto mode update-alternatives: using /usr/share/man/man5/maildir.courier.5.gz to provide /usr/share/man/man5/maildir.5.gz (maildir.5.gz) in auto mode update-alternatives: using /usr/bin/maildirmake.courier to provide /usr/bin/maildirmake (maildirmake) in auto mode update-alternatives: using /usr/share/man/man7/maildirquota.courier.7.gz to provide /usr/share/man/man7/maildirquota.7.gz (maildirquota.7.gz) in auto mode update-alternatives: using /usr/bin/makedat.courier to provide /usr/bin/makedat (makedat) in auto mode Setting up courier-mta (0.68.2-1) ... update-alternatives: using /usr/bin/lockmail.courier to provide /usr/bin/lockmail (lockmail) in auto mode update-alternatives: using /usr/bin/preline.courier to provide /usr/bin/preline (preline) in auto mode Starting Courier mail server: done. Starting Courier mail filter: done. Starting Courier SMTP server: done. Current status: 0 broken [-2]. # The problem courier-mta appeared to have installed without error, and yet courier-mta is not installed. Instead, sendmail is installed: root@treebeard:/etc/logcheck/violations.ignore.d$ dpkg -l 'courier*' 'sendmail*' 'exim*' sensible-mda Desired=Unknown/Install/Remove/Purge/Hold | Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend |/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad) ||/ Name Version Architecture Description +++-===============================================-============================-============================-=================================================================================================== ii courier-authdaemon 0.63.0-6+b1 i386 Courier authentication daemon ii courier-authlib 0.63.0-6+b1 i386 Courier authentication library ii courier-authlib-userdb 0.63.0-6+b1 i386 userdb support for the Courier authentication library un courier-authmysql (no description available) un courier-authpostgresql (no description available) ii courier-base 0.68.2-1 i386 Courier mail server - base system un courier-debug (no description available) un courier-doc (no description available) un courier-faxmail (no description available) un courier-filter-perl (no description available) un courier-imap (no description available) rc courier-mta 0.68.2-1 i386 Courier mail server - ESMTP daemon un couriergrey (no description available) un exim4 (no description available) ii sendmail 8.14.4-4 all powerful, efficient, and scalable Mail Transport Agent ii sendmail-base 8.14.4-4 all powerful, efficient, and scalable Mail Transport Agent ii sendmail-bin 8.14.4-4 i386 powerful, efficient, and scalable Mail Transport Agent ii sendmail-cf 8.14.4-4 all powerful, efficient, and scalable Mail Transport Agent un sendmail-doc (no description available) un sendmail-tls (no description available) ii sensible-mda 8.14.4-4 i386 Mail Delivery Agent wrapper sendmail-bin (and its requirements) have been installed. Packages required by courier-mta have been installed, but courier-mta itself has not. # History This is a Debian Wheezy (stable) box. It was running Debian Jessy (testing), but I downgraded it to Wheezy by means of this /etc/apt/preferences file: Package: * Pin: release a=stable Pin-Priority: 1001 and by changing /etc/apt/sources file to: deb http://ftp.debian.org/debian wheezy main non-free contrib deb http://security.debian.org/ wheezy/updates main contrib non-free and by a means of a long series of apt-get/dpkg commands which I do not recall. I do recall there being much swearing. # The question **Why, when I try to install courier-mta, is sendmail-bin being installed instead?**