Simple mail server
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/