root@mailserver:/etc/apt# apt-get install -y libboost-all-dev libdb++-dev libgmp-dev libssl-dev dos2unix
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package libdb++-dev is a virtual package provided by:
  libdb4.6++-dev 4.6.21-16
  libdb4.8++-dev 4.8.24-1ubuntu1
  libdb4.7++-dev 4.7.25-9
You should explicitly select one to install.
E: Package libdb++-dev has no installation candidate