Before installation mysite.com MX record points to mysite.com **Step 1** Need to do https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-postfix-on-ubuntu-16-04 **Step 2** Setup all, except ClamAV (if RAM is enough, ClamAV can be installed) https://help.ubuntu.com/community/PostfixAmavisNew How to siable ClamAV: # @\bypass_virus_checks_maps = ( # \%bypass_virus_checks, \@\bypass_virus_checks_acl, \$bypass_virus_checks_re); **Step 3** Instead Dovecot i prefer this https://help.ubuntu.com/community/PostfixBasicSetupHowto Installing courier IMAP and POP3 apt install courier-pop apt install courier-imap Then service courier-authdaemon start systemctl enable courier-authdaemon /etc/init.d/postfix restart **Step 4** Setup SPF https://www.digitalocean.com/community/tutorials/how-to-create-a-spf-record-for-your-domain-with-google-apps **Step 5** Setup DKIM https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-dkim-with-postfix-on-debian-wheezy **Step 6** Setup DMARK https://habrahabr.ru/company/mailru/blog/170957/