Mail working on a domain needs four DNS records you never see in a browser. Each answers a different question; if one is missing, mail either never arrives or lands in spam.
The MX record answers "which server should mail for this domain go to." For mailkodo.com, it points to mx.ovokodo.com — the mail server lives in Helsinki, while domain management can live elsewhere; MX is the link between the two.
SPF (Sender Policy Framework) is the list of "who is allowed to send mail for this domain" — it sits in DNS as a text record, and receiving servers compare incoming mail's sending server against that list.
DKIM signs every outgoing message with the server's private key; the recipient checks that signature against the public key sitting in the domain's DNS. SPF answers "which server," DKIM answers "did the mail change on the way."
DMARC combines the outcome of both and tells the receiving server what to do when SPF or DKIM fails (ignore, mark as spam, reject) and sends a report back to the domain owner. Together, the three make it harder to send forged mail on a domain's behalf.
mailkodo already sets up and manages these four records for its own shared @mailkodo.com domain — your mailbox opens as part of that, and you never touch a DNS panel. For mail on your own domain ("[email protected]"), leave a request on the Domain page: setup is planned after scope and price are confirmed, and mailboxes are not opened automatically. You, or whoever manages that domain, add the four records to its DNS.