I ran the following:

sudo apt-get remove postfix mailutils libsasl2-2 ca-certificates libsasl2-modules

Why would that command do the following and what's the best way to undo it?

Reading package lists... Done

Building dependency tree       

Reading state information... Done

The following packages were automatically installed and are no longer required:

  couchdb-common erlang-asn1 erlang-base-hipe erlang-crypto erlang-eunit

  erlang-inets erlang-mnesia erlang-os-mon erlang-public-key

  erlang-runtime-tools erlang-snmp erlang-ssl erlang-syntax-tools erlang-tools

  erlang-webtool erlang-xmerl gtk2-engines libbit-vector-perl

  libcarp-clan-perl libclass-data-inheritable-perl

  libclass-method-modifiers-perl libcommon-sense-perl

  libcrypt-openssl-bignum-perl libcrypt-openssl-rsa-perl libdata-random-perl

  libdate-calc-perl libdate-calc-xs-perl libenet2a libextutils-depends-perl

  libextutils-pkgconfig-perl libgd-perl libgnome2-canvas-perl

  libgnome2-wnck-perl libgoo-canvas-perl libgoocanvas-common libgoocanvas3

  libgtk2-appindicator-perl libgtk2-imageview-perl libgtk2-unique-perl

  libgtkimageview0 libhttp-server-simple-perl libjs-prototype

  libjs-scriptaculous libjson-perl libjson-xs-perl libmouse-perl

  libmozjs185-1.0 libpath-class-perl libproc-processtable-perl

  libproc-simple-perl libsctp1 libsort-naturally-perl libtie-ixhash-perl

  libunique-1.0-0 libx11-protocol-perl libxml-xpathengine-perl lksctp-tools

  perlmagick supertuxkart-data

Use 'apt-get autoremove' to remove them.

The following extra packages will be installed:

  libxml-libxml-perl

The following packages will be REMOVED

  account-plugin-aim account-plugin-yahoo aisleriot apt-transport-https apturl

  atom ca-certificates checkbox-gui checkbox-ng checkbox-ng-service

  chromium-browser chromium-browser-l10n compiz compiz-gnome couchdb

  couchdb-bin curl darktable deja-dup-backend-gvfs evolution-data-server

  gconf-service gconf-service-backend gconf2 gir1.2-gdata-0.0 git

  gnome-contacts gnome-terminal gnome-terminal-data gnome-user-share

  gstreamer0.10-plugins-bad gstreamer1.0-plugins-bad gvfs-backends

  indicator-applet kerneloops-daemon libbonoboui2-0 libcmis-0.4-4 libcurl3

  libcurl3-gnutls libflickcurl0 libfolks-eds25 libgconf2-4 libgdata13

  libgnome2-0 libgnome2-bin libgnome2-common libgnome2-gconf-perl

  libgnome2-perl libgnome2-vfs-perl libgnomeui-0 libgnomevfs2-0

  libgnomevfs2-common libgnomevfs2-extra libldap-2.4-2 libldb1

  liblwp-protocol-https-perl libmailutils4 libnet-dbus-perl

  libnet-dropbox-api-perl libnet-oauth-perl liboauth0 libpanel-applet-4-0

  libpurple0 libraptor2-0 librasqal3 librdf0

  libreoffice-avmedia-backend-gstreamer libreoffice-base-core libreoffice-calc

  libreoffice-core libreoffice-draw libreoffice-gnome libreoffice-gtk

  libreoffice-help-en-us libreoffice-impress libreoffice-math

  libreoffice-ogltrans libreoffice-pdfimport

  libreoffice-presentation-minimizer libreoffice-writer libruby1.9.1

  libsasl2-2 libsasl2-modules libslv2-9 libsmbclient libspice-server1

  libwww-mechanize-perl libwww-perl libxml-parser-perl libxml-sax-expat-perl

  libxml-twig-perl mailutils mythes-en-us nautilus-share network-manager-gnome

  oneconf oneconf-common postfix python-cupshelpers python-gconf python-gnome2

  python-httplib2 python-ldb python-oneconf python-piston-mini-client

  python-pycurl python-requests python-samba python-smbc

  python-ubuntu-sso-client python3-checkbox-ng python3-httplib2

  python3-oneconf python3-piston-mini-client python3-pycurl python3-requests

  python3-software-properties python3-uno redshift ruby ruby1.9.1

  samba-common-bin samba-libs seahorse shutter smbclient software-center

  software-center-aptdaemon-plugins software-properties-common

  software-properties-gtk spotify-client steam-launcher supertuxkart

  system-config-printer-common system-config-printer-gnome

  system-config-printer-udev telepathy-haze transmission-gtk ubuntu-desktop

  ubuntu-sso-client ubuntu-sso-client-qt unity unity-lens-photos

  unity-scope-gdrive unity-scope-musicstores vlc vlc-nox vlc-plugin-notify

  vlc-plugin-pulse whoopsie xserver-xorg-video-all xserver-xorg-video-qxl

The following NEW packages will be installed

  libxml-libxml-perl

0 to upgrade, 1 to newly install, 151 to remove and 9 not to upgrade.

Need to get 337 kB of archives.

After this operation, 1,072 MB disk space will be freed.

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