What is DKIM?

DKIM (DomainKeys Identified Mail) is an email security standard that helps detect whether messages are altered in transit between sending and receiving mailservers.

DKIM authentication uses public-key cryptography to sign email with a responsible party’s private key as it leaves a sending server; recipient servers then use a public key published to the DKIM’s domain to verify the source of the message, and that the parts of the message included in the DKIM signature haven’t changed since the message was signed. Once the signature is verified with the public key by the recipient server, the message passes DKIM and is considered authentic.

What is a DKIM record?

A DKIM record is a specially formatted DNS TXT record; it stores the public key the receiving mail server will use to verify a message’s signature.

A DKIM record is formed by a name, version, key type, and the public key itself, and is often made available by the provider that is sending your email (for example, Magnetiq. That’s us 👋).

Two key reasons why DKIM is important

1. It confirms your legitimacy as a sender

Spoofing email from trusted domains is a popular technique for malicious spam and phishing campaigns, and DKIM makes it harder to spoof email from domains that use it. While DKIM isn’t required, having emails that are signed with DKIM appear more legitimate to your recipients and are less likely to end up in the junk or spam folders.

DKIM is compatible with existing email infrastructure and works with SPF and DMARC to create multiple layers of security for domains sending emails. Mail servers that don’t support DKIM signatures are still able to receive signed messages without any problems. It’s an optional security protocol, and DKIM is not a universally adopted standard.

Even though it’s not required, we recommend you add a DKIM record to your DNS whenever possible to authenticate mail from your domain. We use it to sign messages at Magnetiq, and ISPs like Yahoo, AOL, and Gmail use it to check incoming messages. We’ve done testing that proved messages are more likely to be delivered when they use these security protocols.

2. It helps build your long-term reputation

An additional benefit of DKIM is that ISPs use it to build a domain reputation over time. As you send email and improve your delivery practices (low spam and bounces, high engagement), you help your domain build a good sending reputation with ISPs, which improves email deliverability.

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