DNS Records

Before we go further, we need to create an A record and an MX record fo our mailserver domain. This can be done easily using the previously set up Cloudflare DNS management. If using another supplier then please consult their documentation for setting up DNS records.

Some guides for popular domain registrars are below:

GoDaddy: https://uk.godaddy.com/help/change-an-mx-record-19235
DreamHost: https://help.dreamhost.com/hc/en-us/articles/215035328-How-do-I-change-my-MX-records-
Namecheap: https://www.namecheap.com/support/knowledgebase/article.aspx/322/2237/how-can-i-set-up-mx-records-required-for-mail-service
HostGator: https://www.hostgator.com/help/article/changing-dns-records
BlueHost: https://my.bluehost.com/hosting/help/mx

The MX record should point to the hostname of your server ie hostname.example.com

The A record should be for the host name ie hostname.example.com, and should point to your servers public IP address

Further information: https://www.copernica.com/en/blog/post/a-record-and-mx-record-how-does-it-work