Enable DKIM for plesk 12.x

Hello,

Is there any guide how to enable DKIM for Plesk ?
I dont find any simple guide which only handles how to enable DKIM for Plesk
Does plesk use Postfix ? should I install amavisd or ClamAV to enable DKIM ?

I think Cpanel has oneclick feature, for enabling DKIM.
So this message is Plesk Improvment suggestion at the same time

Im using Ubuntu 14.04 with Webadmin Plesk 12