post_install(){
 echo "To add an ed25519 signature, first run \`dknewkey -k ed25519 selectorname\`
to generate a new keypair, then add to \"/etc/dkimpy-milter/dkimpy-milter.conf\"
the following lines:

    KeyFileEd25519  /path/to/selectorname.key
    SelectorEd25519 selectorname

To configure postfix, add to \"/etc/postfix/main.conf\" the following lines:

    smtpd_milters = unix:/var/run/dkimpy-milter/dkimpy-milter.sock
    non_smtpd_milters = $smtpd_milters
    milter_default_action = accept

You will also need to modify \"/etc/postfix/master.cf\" and add the following directives:

    smtp            inet  n      -      n      -     -      smtpd
     -o milter_macro_daemon_name=VERIFYING

    submission      inet  n      -      n      -     -      smtpd
     -o milter_macro_daemon_name=ORIGINATING

    submissions     inet  n      -      n      -     -      smtpd
     -o milter_macro_daemon_name=ORIGINATING
  
Don't forget to change the socket permissions in '/etc/dkimpy-milter/dkimpy-milter.conf'
according to your MTA user group:

    UserID                  dkimpy-milter:postfix
"
}

post_upgrade(){
 post_install $1
}