root@gspp:/var/log# apt-get install dovecot
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package dovecot is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
However the following packages replace it:
  dovecot-common

E: Package 'dovecot' has no installation candidate
root@gspp:/var/log# apt-get remove dovecot
Reading package lists... Done
Building dependency tree
Reading state information... Done
Virtual packages like 'dovecot' can't be removed
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
root@gspp:/var/log# apt-get purge dovecot
Reading package lists... Done
Building dependency tree
Reading state information... Done
Virtual packages like 'dovecot' can't be removed
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
root@gspp:/var/log#