Safeguard your emails with SPF, DKIM and DMARC Safeguard your emails wit...

Safeguard your emails with SPF, DKIM and DMARC


In 2022, the number of global email users amounted to 4.26 billion and is set to grow to 4.73 billion in 2026. Email deliverability is important because it determines if your emails reach their intended recipients. When emails are delivered, they can help build trust and credibility with an audience, increase engagement rates, and improve customer relationships. As a DNS and email service provider, Dynu provides with the tools to set up the DNS records needed for better email delivery.

Dynu Email Network Tools
SPF (Sender Policy Framework)

A Sender Policy Framework (SPF) record tells the rest of the Internet which email servers are allowed to send emails for a domain. This helps reduce spam by letting the recipient's mail servers check an email's sending IP against the domain's SPF record. If the two do not match, the recipient's mail server has the option to reject the message or flag it as spam. Gmail requires at least one of SPF or DKIM to be set up to be able to deliver to Gmail. You can use our SPF Generator tool to generate an SPF record for your domain name.

Error Type: SMTP
Remote server ( issued an error.
Remote server replied: 550-5.7.26 This mail is unauthenticated, which poses a security
550-5.7.26 risk to the sender and Gmail users, and has been blocked. The sender must
550-5.7.26 authenticate with at least one of SPF or DKIM . For this message,
550-5.7.26 DKIM checks did not pass and SPF check for [] did not
550-5.7.26 pass with ip: []. The sender should visit
550-5.7.26 for
550 5.7.26 instructions on setting up authentication.
o5-20020a170906774500b008c580ab8d9esi8642798ejn.69 - gsmtp

DKIM (Domain Keys Identified Email)

DKIM stands for Domain Keys Identified Email and it is a way of 'signing' emails to prove they are delivered by the organization that has the right to do so and prevents spammers from stealing the identity of legitimate entities. DKIM uses a pair of public and private keys - the private key is known only to you and is stored on the sending mail server to create the signature. The public key is available to anyone and can be used to verify that the correct private key was used. Our DKIM Generator tool allows you to easily create a public and private key pair to be used for DomainKeys and DKIM signing.


Similar to SPF and DKIM, DMARC is another form of email authentication to prevent spammers from sending emails using your domain. DMARC stands for Domain-Based Message Authentication, Reporting and Conformance. It allows domain owners to set up domain-level policies on mail handling including preferences for message verification, failure handling, and reporting. DMARC is not mandatory by most Email Service Providers and like many other deliverability practices, using DMARC will not ensure your emails go to the inbox. However, visibility through report-based feedback is a DMARC feature that truly stands out. You can use our DMARC tool to generate a DMARC record that works for you by answering some simple questions. When first enabling DMARC ecord, it is best that you start with the least strict setting (p=none) and then progressively move up.

If you have any questions or concerns, open a support ticket and we'd be glad to assist you.

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