root@vmi160223:~# apt-cache showpkg postfix
Package: postfix
Versions:
3.1.6-0+deb9u1 (/var/lib/apt/lists/asi-fs-n.contabo.net_debian_dists_stretch_main_binary-amd64_Packages) (/var/lib/dpkg/status)
 Description Language:
                 File: /var/lib/apt/lists/asi-fs-n.contabo.net_debian_dists_stretch_main_binary-amd64_Packages
                  MD5: 98656fbf1bb45b53edd367037a2e5a90
 Description Language: en
                 File: /var/lib/apt/lists/asi-fs-n.contabo.net_debian_dists_stretch_main_i18n_Translation-en
                  MD5: 98656fbf1bb45b53edd367037a2e5a90


Reverse Depends:
  postfix-cdb,postfix 3.1.3-7~
  virtualmin-lemp-stack-minimal,postfix
  virtualmin-lemp-stack-minimal,postfix
  virtualmin-lemp-stack-minimal,postfix
  virtualmin-lemp-stack-minimal,postfix
  virtualmin-lemp-stack-minimal,postfix
  virtualmin-lemp-stack-minimal,postfix
  virtualmin-lemp-stack,postfix
  virtualmin-lemp-stack,postfix
  virtualmin-lemp-stack,postfix
  virtualmin-lemp-stack,postfix
  virtualmin-lemp-stack,postfix
  virtualmin-lemp-stack,postfix
  virtualmin-lemp-stack,postfix
  virtualmin-lamp-stack-minimal,postfix
  virtualmin-lamp-stack-minimal,postfix
  virtualmin-lamp-stack-minimal,postfix
  virtualmin-lamp-stack-minimal,postfix
  virtualmin-lamp-stack-minimal,postfix
  virtualmin-lamp-stack-minimal,postfix
  virtualmin-lamp-stack,postfix
  virtualmin-lamp-stack,postfix
  virtualmin-lamp-stack,postfix
  virtualmin-lamp-stack,postfix
  virtualmin-lamp-stack,postfix
  virtualmin-lamp-stack,postfix
  virtualmin-lamp-stack,postfix
  exim4-config,postfix
  fex,postfix
  vmm,postfix
  uucp,postfix
  tripwire,postfix
  sqlgrey,postfix
  spamass-milter,postfix
  sks,postfix
  sendpage-server,postfix
  rmail,postfix
  reportbug,postfix
  reboot-notifier,postfix
  postfix-policyd-spf-python,postfix
  spf-milter-python,postfix 2.3
  dkim-milter-python,postfix 2.3
  python-milter,postfix 2.3
  proxsmtp,postfix
  postgrey,postfix
  postfix-policyd-spf-perl,postfix
  postfix-gld,postfix 2.1
  postfix-sqlite,postfix 3.1.3-7~
  postfix-sqlite,postfix 3.1.6-0+deb9u1
  postfix-pgsql,postfix 3.1.3-7~
  postfix-pgsql,postfix 3.1.3-7~
  postfix-pgsql,postfix 3.1.6-0+deb9u1
  postfix-pcre,postfix 3.1.3-7~
  postfix-pcre,postfix 3.1.3-7~
  postfix-pcre,postfix 3.1.6-0+deb9u1
  postfix-mysql,postfix 3.1.3-7~
  postfix-mysql,postfix 3.1.3-7~
  postfix-mysql,postfix 3.1.6-0+deb9u1
  postfix-lmdb,postfix 3.1.3-7~
  postfix-lmdb,postfix 3.1.3-7~
  postfix-lmdb,postfix 3.1.6-0+deb9u1
  postfix-ldap,postfix 3.1.3-7~
  postfix-ldap,postfix 3.1.3-7~
  postfix-ldap,postfix 3.1.6-0+deb9u1
  postfix-doc,postfix
  postfix-cdb,postfix 3.1.6-0+deb9u1
  libsasl2-2,postfix 2.8.3-1
  policyd-rate-limit,postfix
  pmailq,postfix
  pfqueue,postfix
  mysqmail-postfix-logger,postfix
  monitoring-plugins-standard,postfix
  monit,postfix
  mlmmj,postfix
  mixmaster,postfix
  mimedefang,postfix
  milter-greylist,postfix
  mailgraph,postfix
  mailagent,postfix
  iwatch,postfix
  hobbit-plugins,postfix
  gross,postfix
  gitlab,postfix
  fwlogwatch,postfix
  exim4-config,postfix
  echolot,postfix
  drac,postfix
  amavisd-milter,postfix
  cron,postfix
  clamsmtp,postfix
  bley,postfix
  bld-postfix,postfix
Dependencies:
3.1.6-0+deb9u1 - libc6 (2 2.14) libdb5.3 (0 (null)) libicu57 (2 57.1-1~) libsasl2-2 (0 (null)) libssl1.1 (2 1.1.0) debconf (18 0.5) debconf-2.0 (0 (null)) init-system-helpers (2 1.18~) netbase (0 (null)) adduser (2 3.48) dpkg (2 1.8.3) lsb-base (2 3.0-6) ssl-cert (0 (null)) cpio (0 (null)) postfix-sqlite (0 (null)) mail-transport-agent (0 (null)) smail (0 (null)) python3 (0 (null)) procmail (0 (null)) postfix-mysql (0 (null)) postfix-pgsql (0 (null)) postfix-ldap (0 (null)) postfix-pcre (0 (null)) postfix-lmdb (0 (null)) sasl2-bin (0 (null)) libsasl2-modules (0 (null)) dovecot-common (0 (null)) resolvconf (0 (null)) postfix-cdb (0 (null)) mail-reader (0 (null)) ufw (0 (null)) postfix-doc (0 (null)) mail-transport-agent (0 (null))
Provides:
3.1.6-0+deb9u1 - mail-transport-agent (= )
Reverse Provides:
root@vmi160223:~#