DomainKeys Identified Mail (DKIM) is a technology that allows an organization to vouch for the messages it sends out by e-mail. To put it in technical terms, it is a method of confirming the sender’s domain by meanings of a cryptographic signature.
Will DKIM help ensure that my e-mails are delivered?
Everything depends on the servers that validate the e-mails. When you sign your e-mails using DKIM, the receiving server looks at the credentials of the company that sent the e-mail and it decides what to do with the message. E-mails from companies with a good reputation will undergo less filtering on the recipient’s end.