--- title: "DKIM: The Secret to Improved Email Deliverability | OutboundSMTP" description: "Discover how DKIM authentication works to improve email deliverability by verifying sender identity through cryptographic signatures in DNS." image: "https://outboundsmtp.com/og/blog/dkim-the-secret-to-improved-email-deliverability.png" canonical: "https://outboundsmtp.com/blog/dkim-the-secret-to-improved-email-deliverability/" --- Quick Answer DKIM (DomainKeys Identified Mail) improves email deliverability by attaching a cryptographic signature to outbound messages that receiving servers verify against a public key published in your DNS records. When the signature matches, the email is proven authentic and unaltered in transit, which reduces spam filtering and improves inbox placement with providers like Gmail and Office 365. Share [ ](https://www.linkedin.com/sharing/share-offsite/?url=https%3A%2F%2Foutboundsmtp.com%2Fblog%2Fdkim-the-secret-to-improved-email-deliverability%2F "Share on LinkedIn") [ ](https://twitter.com/intent/tweet?text=DKIM%3A%20The%20Secret%20to%20Improved%20Email%20Deliverability&url=https%3A%2F%2Foutboundsmtp.com%2Fblog%2Fdkim-the-secret-to-improved-email-deliverability%2F "Share on X/Twitter") [ ](https://www.facebook.com/sharer/sharer.php?u=https%3A%2F%2Foutboundsmtp.com%2Fblog%2Fdkim-the-secret-to-improved-email-deliverability%2F "Share on Facebook") [ ](https://reddit.com/submit?url=https%3A%2F%2Foutboundsmtp.com%2Fblog%2Fdkim-the-secret-to-improved-email-deliverability%2F&title=DKIM%3A%20The%20Secret%20to%20Improved%20Email%20Deliverability "Share on Reddit") [ ](mailto:?subject=DKIM%3A%20The%20Secret%20to%20Improved%20Email%20Deliverability&body=Check out this article: https%3A%2F%2Foutboundsmtp.com%2Fblog%2Fdkim-the-secret-to-improved-email-deliverability%2F "Share via Email") ![SMTP inbox deliverability with DKIM](https://media.mailhop.org/outboundsmtp/images/blog/smtp-inbox.jpg) The secret to improved email deliverability isn’t in your email server. It’s actually in your DNS server. That’s because the DNS server record is where you’ll publish a cryptographic public key as a specially-formatted TXT record. And that cryptographic key is the crucial element in email deliverability because it supports email delivery with DKIM. DKIM enables you to send authenticated emails, and authenticated emails look less like spam and are therefore more likely to make it into the inboxes. When a mail message is sent by an outbound mail server, the server generates and attaches a unique DKIM signature header to the message. This header includes two cryptographic hashes, one of specified headers, and one of the message body (or part of it). The header contains information about how the signature was generated. When an inbound mail server receives an incoming email, it looks up the sender’s public DKIM key in DNS. The inbound server uses this key to decrypt the signature and compare it against a freshly computed version. If the two values match, the message can be proved to be authentic and unaltered in transit. DKIM is the secret to improved email deliverability because it’s designed to detect forged sender addresses in emails. Consequently, DKIM signing improves the inbox placement of mailbox providers like Gmail and Office365. ## High Deliverability If you want to ensure high deliverability rates of your high volume emails, you’re going to need correctly configured DKIM signatures in your outbound emails. And if you’re not sure how to do it, then you need to find an outbound SMTP service provider who does know. In addition to correctly formatted DKIM signed emails, a quality outbound SMTP provider also offers correctly configured SPF and DMARC records. They optimize your sending routes and closely monitor your IP reputation to ensure you the best possible delivery rates. A zero spam policy allows blocking or restricting messages that would damage reputation. When you want to ensure your emails get delivered, look for an outbound SMTP service that sets up in minutes and comes with live 24/7 technical support. ## Topics [ DKIM ](/tags/dkim/)[ Email Authentication ](/tags/email-authentication/)[ Email Deliverability ](/tags/email-deliverability/) ![Brad Slavin](https://media.mailhop.org/outboundsmtp/images/authors/brad-slavin.jpg) [ Brad Slavin ](/authors/brad-slavin/) General Manager & Founder General Manager & Founder of DuoCircle. Expert in email deliverability, authentication, and enterprise SMTP infrastructure. [LinkedIn Profile →](https://www.linkedin.com/in/bradslavin/) ## Ready to start sending? Enterprise SMTP relay with dedicated IPs, full authentication, and expert support. Start free. [Start Free Trial](https://insight.iljmp.com/4/smtp-free) [View Pricing](/pricing/) ## Related Articles [ Advanced Bulk Email Services: Know How Email Authentication Helps To Deliver Emails To Customers' Inboxes Nov 25, 2024 ](/blog/bulk-email-services-know-how-email-authentication-helps-to-deliver-emails-to-customers-inboxes/)[ Foundational How to Keep Your Emails Out of Spam Folders Jan 30, 2024 ](/blog/how-to-keep-your-emails-out-of-spam-folders/)[ Advanced Why Google's 'p=none' DMARC Policy Is Just the Beginning: A 2025 Email Security Prediction Jan 20, 2025 ](/blog/why-googles-p-none-dmarc-policy-is-just-the-beginning-a-2025-email-security-prediction/)[ Intermediate An Analysis On Email Blacklists & How You Can Avoid Them For A Successful Email Marketing Campaign Oct 15, 2024 ](/blog/an-analysis-on-email-blacklists-how-you-can-avoid-them-for-a-successful-email-marketing-campaign/) ```json {"@context":"https://schema.org","@type":"Organization","name":"OutboundSMTP","url":"https://outboundsmtp.com","logo":{"@type":"ImageObject","url":"https://outboundsmtp.com/images/outboundsmtp-logo.png"},"description":"Enterprise SMTP relay service by DuoCircle. Dedicated IPs, sub-accounts, full authentication, and reliable email delivery for businesses of all sizes.","parentOrganization":{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138883901","name":"DuoCircle LLC","url":"https://www.duocircle.com","sameAs":["https://www.wikidata.org/wiki/Q138883901","https://www.crunchbase.com/organization/duocircle-llc","https://www.linkedin.com/company/duocircle","https://github.com/duocircle"],"subOrganization":[{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138898167","name":"DMARC Report","url":"https://dmarcreport.com"},{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138897474","name":"AutoSPF","url":"https://autospf.com"},{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138897912","name":"Phish Protection","url":"https://www.phishprotection.com"}]},"sameAs":["https://www.linkedin.com/company/duocircle","https://www.facebook.com/duocircle/","https://x.com/duocircle","https://github.com/duocircle"],"contactPoint":{"@type":"ContactPoint","contactType":"customer support","url":"https://outboundsmtp.com/contact-us/"},"knowsAbout":["SMTP Relay","Email Delivery","Email Infrastructure","Dedicated IP Addresses","Email Authentication","SPF","DKIM","DMARC","Transactional Email","Outbound Email"]} ``` ```json {"@context":"https://schema.org","@type":"WebSite","name":"OutboundSMTP","url":"https://outboundsmtp.com","description":"Enterprise SMTP relay service by DuoCircle. Dedicated IPs, sub-accounts, full authentication, and reliable email delivery for businesses of all sizes.","publisher":{"@type":"Organization","name":"OutboundSMTP","url":"https://outboundsmtp.com","logo":{"@type":"ImageObject","url":"https://outboundsmtp.com/images/outboundsmtp-logo.png"},"description":"Enterprise SMTP relay service by DuoCircle. Dedicated IPs, sub-accounts, full authentication, and reliable email delivery for businesses of all sizes.","parentOrganization":{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138883901","name":"DuoCircle LLC","url":"https://www.duocircle.com","sameAs":["https://www.wikidata.org/wiki/Q138883901","https://www.crunchbase.com/organization/duocircle-llc","https://www.linkedin.com/company/duocircle","https://github.com/duocircle"],"subOrganization":[{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138898167","name":"DMARC Report","url":"https://dmarcreport.com"},{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138897474","name":"AutoSPF","url":"https://autospf.com"},{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138897912","name":"Phish Protection","url":"https://www.phishprotection.com"}]}}} ``` ```json {"@context":"https://schema.org","@type":"BlogPosting","headline":"DKIM: The Secret to Improved Email Deliverability","description":"Discover how DKIM authentication works to improve email deliverability by verifying sender identity through cryptographic signatures in DNS.","url":"https://outboundsmtp.com/blog/dkim-the-secret-to-improved-email-deliverability/","datePublished":"2024-10-15T00:00:00.000Z","dateModified":"2026-04-18T00:00:00.000Z","dateCreated":"2024-10-15T00:00:00.000Z","author":{"@type":"Person","@id":"https://outboundsmtp.com/authors/brad-slavin/#person","name":"Brad Slavin","url":"https://outboundsmtp.com/authors/brad-slavin/","jobTitle":"General Manager & Founder","description":"Brad Slavin is the General Manager and Founder of DuoCircle, a company that provides comprehensive email security solutions including OutboundSMTP enterprise relay services. With decades of experience in the email industry, Brad specializes in email deliverability, authentication, and infrastructure.","image":"https://media.mailhop.org/outboundsmtp/images/authors/brad-slavin.jpg","knowsAbout":["Email Deliverability","SMTP Infrastructure","Email Authentication","SPF","DKIM","DMARC","Enterprise Email"],"worksFor":{"@type":"Organization","name":"OutboundSMTP","url":"https://outboundsmtp.com"},"sameAs":["https://www.linkedin.com/in/bradslavin/","https://x.com/duocircle","https://outboundsmtp.com"]},"publisher":{"@type":"Organization","name":"OutboundSMTP","url":"https://outboundsmtp.com","logo":{"@type":"ImageObject","url":"https://outboundsmtp.com/images/outboundsmtp-logo.png"},"description":"Enterprise SMTP relay service by DuoCircle. Dedicated IPs, sub-accounts, full authentication, and reliable email delivery for businesses of all sizes.","parentOrganization":{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138883901","name":"DuoCircle LLC","url":"https://www.duocircle.com","sameAs":["https://www.wikidata.org/wiki/Q138883901","https://www.crunchbase.com/organization/duocircle-llc","https://www.linkedin.com/company/duocircle","https://github.com/duocircle"],"subOrganization":[{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138898167","name":"DMARC Report","url":"https://dmarcreport.com"},{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138897474","name":"AutoSPF","url":"https://autospf.com"},{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138897912","name":"Phish Protection","url":"https://www.phishprotection.com"}]},"sameAs":["https://www.linkedin.com/company/duocircle","https://www.facebook.com/duocircle/","https://x.com/duocircle","https://github.com/duocircle"],"contactPoint":{"@type":"ContactPoint","contactType":"customer support","url":"https://outboundsmtp.com/contact-us/"},"knowsAbout":["SMTP Relay","Email Delivery","Email Infrastructure","Dedicated IP Addresses","Email Authentication","SPF","DKIM","DMARC","Transactional Email","Outbound Email"]},"mainEntityOfPage":{"@type":"WebPage","@id":"https://outboundsmtp.com/blog/dkim-the-secret-to-improved-email-deliverability/"},"articleSection":"advanced","keywords":"DKIM, Email Authentication, Email Deliverability","image":{"@type":"ImageObject","url":"https://media.mailhop.org/outboundsmtp/images/blog/smtp-inbox.jpg","caption":"SMTP inbox deliverability with DKIM"},"speakable":{"@type":"SpeakableSpecification","cssSelector":[".answer-block","h1"]}} ``` ```json {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://outboundsmtp.com/"},{"@type":"ListItem","position":2,"name":"Blog","item":"https://outboundsmtp.com/blog/"},{"@type":"ListItem","position":3,"name":"Advanced","item":"https://outboundsmtp.com/advanced/"},{"@type":"ListItem","position":4,"name":"DKIM: The Secret to Improved Email Deliverability","item":"https://outboundsmtp.com/blog/dkim-the-secret-to-improved-email-deliverability/"}]} ```