DomainKeys Identified Mail (DKIM) is a protocol that allows an organization to take responsibility for transmitting a message in a way that can be verified by the mailbox provider. This verification is made possible through cryptographic authentication.
You can help prevent spoofing by adding a digital signature to outgoing message headers using the DKIM standard. This involves using a private domain key to encrypt your domain's outgoing mail headers and adding a public version of the key to the domain's DNS records. Recipient servers can then retrieve the public key to decrypt incoming headers and verify that the message really comes from your domain and hasn't been changed along the way.
If you wish to configure DKIM for your domain, please contact Redtail Email Support via email at email@example.com or via phone at 800.206.5030 to submit a request to have DKIM enabled for your domain.