DomainKeys Identified Mail (DKIM) is an email authentication protocol that allows an organization to transmit a message in a way that their identity can be verified by mailbox providers. Verification is made possible through cryptographic authentication.
When a message has been signed using DKIM, mailbox providers who successfully validate the signature can use information about the signer as part of a program to limit spam, spoofing, and phishing. However, DKIM does not tell mailbox providers to take any specific action if the DKIM signature is not verified. So, mailbox providers weight DKIM verification failures based on their internal spam filter algorithms along with other sending reputation factors to determine if email should be placed in the inbox or spam folder. Depending on the implementation, DKIM can also ensure that the message has not been modified or tampered during transit.
Implementing DKIM is considered to be an industry best practice and is recommended. Talk to your email administrator, hosting provider or email service provider to implement DKIM. Additional information about DKIM and how it is implemented can be found at DKIM.org.
