I just set up postfix on the server but emails could not be received.
I've followed this guide https://www.digitalocean.com/community/tutorials/how-to-install-and-setup-postfix-on-ubuntu-14-04 step by step and tested sending my email from my gmail to both firstname.lastname@example.org and email@example.com. But the emails could not be delivered.
I have added
firstname.lastname@example.org felix in
sudo /etc/postfix/virtual step.
Could it be because I did not add any MX records?