DomainKeys Identified Mail can help you verify your sending sources, and authenticate emails sent from your domain before it reaches your clients. This can ultimately help you minimize spam emails sent from fake IDs.
Unfortunately, Mythic Beasts doesn’t seem to currently support DKIM authentication for domains registered with them. For further information on the same, please contact Mythic Beast’s support team by dropping them a mail at firstname.lastname@example.org.
Alternatively, you can configure SPF for Mythic Beasts.