DKIM is a technique based on Yahoo!’s DomainKey. Some may say that it look alike SPF (Sender Policy Framework), but the two is different. DKIM is authenticating the email sent by checking the signature againts the domain’s public key. On the contrary, SPF check the MTA (mail server) that sends the email againsts the domain’s list of MTA. For the simplicity, let’s say that the sending domain is UI
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