Domain Keys Identified Mail (DKIM) is a technology that allows organizations to vouch for messages sent by email. In technical terms, this is a method of confirming the sender’s domain by means of a cryptographic signature.
Will DKIM improve the deliverability of my emails?
Everything depends on the servers that validate the email. When you sign your emails with DKIM, the recipient will look at the credentials of the company that signed the message, and will then decide what to do with the email. Messages from companies with a good reputation will undergo a less thorough filtering on the recipient’s end.
SPF (Sender Policy Framework) technology is one of the means of identifying the sender of an email and it provides an additional means of filtering emails to determine if any spam is present.
Authentication tells mailboxes that your message is genuine. Authentication by means of DKIM and SPF proves that it was indeed sent out from the sender’s address, which improves the deliverability of the message.