---
title: "DKIM Selector: How It Works And Why It’s Necessary | DuoCircle"
description: "One of the more popular and controversial email marketing techniques these days is DKIM."
image: "https://www.duocircle.com/images/og-default.png"
canonical: "https://www.duocircle.com/blog/email-hosting/dkim-selector-how-it-works-and-why-its-necessary/"
---

Quick Answer

DKIM (DomainKeys Identified Mail) verifies a message came from the claimed sending domain and was not modified in transit. It works by attaching a cryptographic signature to each outbound message, computed with a private key held only by the sender. The receiver looks up the matching public key in DNS and verifies the signature. The DKIM selector in the signature header tells the receiver which DNS record to query (selector.\_domainkey.domain.com). DKIM is a baseline requirement for inbox placement at major providers and is one of the two checks that feed DMARC alignment. Without DKIM, a sender's reputation degrades, replies get marked as suspicious, and the domain becomes easier to spoof.

Share 

[ ](https://www.linkedin.com/sharing/share-offsite/?url=undefined%2Fblog%2Femail-hosting%2Fdkim-selector-how-it-works-and-why-its-necessary%2F "Share on LinkedIn") [ ](https://twitter.com/intent/tweet?text=DKIM%20Selector%3A%20How%20It%20Works%20And%20Why%20It%E2%80%99s%20Necessary&url=undefined%2Fblog%2Femail-hosting%2Fdkim-selector-how-it-works-and-why-its-necessary%2F "Share on X/Twitter") [ ](https://www.facebook.com/sharer/sharer.php?u=undefined%2Fblog%2Femail-hosting%2Fdkim-selector-how-it-works-and-why-its-necessary%2F "Share on Facebook") [ ](https://reddit.com/submit?url=undefined%2Fblog%2Femail-hosting%2Fdkim-selector-how-it-works-and-why-its-necessary%2F&title=DKIM%20Selector%3A%20How%20It%20Works%20And%20Why%20It%E2%80%99s%20Necessary "Share on Reddit") [ ](mailto:?subject=DKIM%20Selector%3A%20How%20It%20Works%20And%20Why%20It%E2%80%99s%20Necessary&body=Check out this article: undefined%2Fblog%2Femail-hosting%2Fdkim-selector-how-it-works-and-why-its-necessary%2F "Share via Email") 

![DomainKeys Identified Mail](https://media.mailhop.org/duocircle/images/2022/07/dmarc-report-7565.jpg) 

One of the more popular and controversial email marketing techniques these days is DKIM. While it’s not entirely a new method, DKIM (**DomainKeys Identified Mail**) is quickly gaining in popularity and may be becoming more necessary in the digital age. DKIM is an email authentication tool that verifies the authenticity of an email. It works by sending DKIM information from an email to a server, which checks that information against public DKIM records before it accepts the message. 

As email and capabilities continue to grow, you want to be sure your sender reputation is staying positive and secure. One of the most effective ways to achieve this goal is the use of [DKIM Selector](/resources/dkim-selector). If the idea of another email address acronym gets you flustered, don t be concerned.

## How does DKIM work?

Once you get past the acronym DKIM, its function is fairly straightforward. It is a variation of an email encryption system where a message recipient has the ability to examine the message to ensure that it is coming from you. Through this method, you let them know that no one else has used your identifier or mail address to pretend to be you.

These email protocols have become the industry-standard, and an email sent without DKIM or SPF may be marked as suspicious by several of the email analysis tools. Here are some of the more involved features of DKIM.

[![DomainKeys Identified Mail](https://media.mailhop.org/duocircle/images/2022/07/windows-smtp-service-7566.jpg)](https://media.mailhop.org/duocircle/images/2022/07/windows-smtp-service-7566.jpg)

## DKIM signature and verification

The main element of DKIM is the DKIM signature. The DKIM signature is a After finishing a message, DKIM signatures are appended to each email address recipient. DKIM signatures may vary from message to message depending on **email recipients** and their content, but will contain some basic parts.

## DKIM records and checks

A DKIM record, also known as a policy for [public-key authentication](https://www.ssh.com/academy/ssh/public-key-authentication) (DKIM), is part of your DNS records. If it does not feature a DKIM record with your individual domain name information, some email providers, like Gmail, implement their own default DKIM for your messages.But, it is always preferable to create some of your own DKIM records. Special, endorsed documents make verification and troubleshooting easier for both sender and recipient.

A DKIM record check is **essentially** an authentication and validation service that checks your DKIM records to make sure they are accurate. There are several tools you can use to check your records, and you will have to make changes whenever you want.

## What are the benefits of using DKIM?

DKIM can easily safeguard the reputation of your business and its email program. It provides [protection from phishing](https://support.microsoft.com/en-au/windows/protect-yourself-from-phishing-0c7ea947-ba98-3bd9-7184-430e1f860a44) and spoofing scams. Your recipients can confirm that your messages and decide if any aren’t legitimate from you. By making use of DKIM, they are much less likely to send private information to scammers.

DKIM improves your organization’s reputation. As your messages can be confirmed, they are very likely to be believed and recognized. Knowing that your emails are protected contributes confidence for recipients when they get in touch with you again. This can help facilitate more communication with your email list , and may even help you strengthen the relationships you have with them.

With DKIM and regular DKIM record checks, you can make sure your email program has the credibility and information it needs to flourish. This way, your sender domain remains associated solely with you, not with spammers who are trying to reach your customers. It’s a simple step that keeps your email communication relevant.

[![protection from phishing](https://media.mailhop.org/duocircle/images/2022/07/email-smtp-service-7567.jpg)](https://media.mailhop.org/duocircle/images/2022/07/email-smtp-service-7567.jpg)

## Key takeaways about DKIM and its usage

Now that we have broken down DKIM into understandable parts, we can review its most important facets. DKIM is a useful service that you should (and should) utilize to verify when sending email to your mailing list. By signing your emails, you indicate that your organization is trustworthy.

DKIM helps you strengthen your reputation and provides the [safety of your emails](/phishing-protection/phishing-protection-voice-authentication-expert-cyber-attackers-break-in-6-attempts/) and your target audience. This small security step can easily be made alongside other best practices, such as ensuring your email list is clean and brushing up your email program to be as secure as possible.

In conclusion, DKIM is for securing email by authenticating whether the message has been tampered with during transmission. The DomainKeys Identified Mail (DKIM) authentication system authenticates an email message by tying it to the **domain** from which it is sent.

![Brad Slavin](https://media.mailhop.org/dmarcreport/images/team/brad-slavin.jpg) 

Brad Slavin 

General Manager

General Manager at DuoCircle. Product strategy and commercial lead across the email security portfolio.

## Secure your email infrastructure

Protect, authenticate, and deliver. Contact our team to find the right solution.

[Contact Sales](/contact/) [Explore Products](/products/) 

Share this article

[ ](https://www.linkedin.com/sharing/share-offsite/?url=https%3A%2F%2Fwww.duocircle.com%2Fblog%2Femail-hosting%2Fdkim-selector-how-it-works-and-why-its-necessary%2F) [ ](https://twitter.com/intent/tweet?text=DKIM%20Selector%3A%20How%20It%20Works%20And%20Why%20It%E2%80%99s%20Necessary&url=https%3A%2F%2Fwww.duocircle.com%2Fblog%2Femail-hosting%2Fdkim-selector-how-it-works-and-why-its-necessary%2F) [ ](https://www.facebook.com/sharer/sharer.php?u=https%3A%2F%2Fwww.duocircle.com%2Fblog%2Femail-hosting%2Fdkim-selector-how-it-works-and-why-its-necessary%2F) Copy 

Related Articles

- [ ![setting up a self-hosted mail server](https://media.mailhop.org/duocircle/images/2026/03/spf-flatterning-5911.jpg)  10 Steps To Set Up A Self-Hosted Mail Server Without Hitting Spam Blog ](/blog/email-hosting/10-steps-set-up-self-hosted-mail-server-avoid-spam/)
- [ ![Moving Mail to the Cloud](https://media.mailhop.org/duocircle/images/2016/04/spf-record-checker-4741.jpg)  The 9 Ways You Benefit from Moving Mail to the Cloud Blog ](/blog/email-hosting/9-ways-benefit-moving-mail-cloud/)
- [  Amazon Order Confirmation Trojan Blog ](/blog/email-hosting/amazon-order-confirmation-trojan/)
- [ ![Zero-day Vulnerability](https://media.mailhop.org/duocircle/images/2021/12/smtp-relay-7593.jpg)  Apache Log4j Zero-day Vulnerability: How to Detect it & Precautions You Need to Take Blog ](/blog/email-hosting/apache-log4j-zero-day-vulnerability-how-to-detect-it-precautions-you-need-to-take/)

## Related Articles

[  Email Hosting 18m  10 Steps To Set Up A Self-Hosted Mail Server Without Hitting Spam  Mar 10, 2026 ](/blog/email-hosting/10-steps-set-up-self-hosted-mail-server-avoid-spam/)[  Email Hosting 5m  The 9 Ways You Benefit from Moving Mail to the Cloud  Apr 13, 2016 ](/blog/email-hosting/9-ways-benefit-moving-mail-cloud/)[  Email Hosting 1m  Amazon Order Confirmation Trojan  Feb 16, 2019 ](/blog/email-hosting/amazon-order-confirmation-trojan/)[  Email Hosting 6m  Apache Log4j Zero-day Vulnerability: How to Detect it & Precautions You Need to Take  Dec 24, 2021 ](/blog/email-hosting/apache-log4j-zero-day-vulnerability-how-to-detect-it-precautions-you-need-to-take/)

```json
{"@context":"https://schema.org","@type":"Organization","name":"DuoCircle LLC","url":"https://www.duocircle.com","logo":{"@type":"ImageObject","url":"https://www.duocircle.com/images/duocircle-logo.png"},"description":"DuoCircle is a portfolio of specialized email products covering protection, authentication, delivery, and routing. We deliver about 90% of category-leader capability at roughly half the price, backed by experts who own the outcome. Trusted by 50,000+ organizations since 2014.","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://x.com/duocirclellc","https://www.facebook.com/duocirclellc","https://www.g2.com/products/phish-protection-by-duocircle/reviews","https://github.com/duocircle","https://www.crunchbase.com/organization/duocircle-llc"],"contactPoint":{"@type":"ContactPoint","contactType":"customer support","url":"https://support.duocircle.com"},"knowsAbout":["Email Security","Email Authentication","SPF","DKIM","DMARC","Phishing Protection","Spam Filtering","SMTP Relay","Email Deliverability","Email Forwarding"]}
```

```json
{"@context":"https://schema.org","@type":"WebSite","name":"DuoCircle LLC","url":"https://www.duocircle.com","description":"DuoCircle is a portfolio of specialized email products covering protection, authentication, delivery, and routing. We deliver about 90% of category-leader capability at roughly half the price, backed by experts who own the outcome. Trusted by 50,000+ organizations since 2014.","publisher":{"@type":"Organization","name":"DuoCircle LLC","url":"https://www.duocircle.com","logo":{"@type":"ImageObject","url":"https://www.duocircle.com/images/duocircle-logo.png"},"description":"DuoCircle is a portfolio of specialized email products covering protection, authentication, delivery, and routing. We deliver about 90% of category-leader capability at roughly half the price, backed by experts who own the outcome. Trusted by 50,000+ organizations since 2014.","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 Selector: How It Works And Why It’s Necessary","description":"One of the more popular and controversial email marketing techniques these days is DKIM.","url":"https://www.duocircle.com/blog/email-hosting/dkim-selector-how-it-works-and-why-its-necessary/","datePublished":"2022-07-13T21:01:19.000Z","dateModified":"2025-05-28T12:18:14.000Z","dateCreated":"2022-07-13T21:01:19.000Z","author":{"@type":"Person","@id":"https://www.duocircle.com/authors/brad-slavin/#person","name":"Brad Slavin","url":"https://www.duocircle.com/authors/brad-slavin/","jobTitle":"General Manager","description":"Brad Slavin runs DuoCircle, the company behind DMARC Report, AutoSPF, Phish Protection, and Mailhop. His focus is product strategy, customer relationships, and the commercial and compliance side of email authentication (DPAs, SLAs, enterprise procurement).","image":"https://media.mailhop.org/dmarcreport/images/team/brad-slavin.jpg","knowsAbout":["Email Security Strategy","SaaS Product Management","Enterprise Compliance","Customer Success","Email Deliverability Business"],"worksFor":{"@type":"Organization","name":"DuoCircle LLC","url":"https://www.duocircle.com"},"sameAs":["https://www.linkedin.com/in/bradslavin"]},"publisher":{"@type":"Organization","name":"DuoCircle LLC","url":"https://www.duocircle.com","logo":{"@type":"ImageObject","url":"https://www.duocircle.com/images/duocircle-logo.png"},"description":"DuoCircle is a portfolio of specialized email products covering protection, authentication, delivery, and routing. We deliver about 90% of category-leader capability at roughly half the price, backed by experts who own the outcome. Trusted by 50,000+ organizations since 2014.","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"}]},"mainEntityOfPage":{"@type":"WebPage","@id":"https://www.duocircle.com/blog/email-hosting/dkim-selector-how-it-works-and-why-its-necessary/"},"articleSection":"email-hosting","keywords":"","wordCount":719,"image":{"@type":"ImageObject","url":"https://media.mailhop.org/duocircle/images/2022/07/dmarc-report-7565.jpg","caption":"DomainKeys Identified Mail","width":900,"height":600},"speakable":{"@type":"SpeakableSpecification","cssSelector":[".answer-block","h1"]}},{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Blog","item":"https://www.duocircle.com/blog/"},{"@type":"ListItem","position":2,"name":"Email Hosting"},{"@type":"ListItem","position":3,"name":"DKIM Selector: How It Works And Why It’s Necessary","item":"https://www.duocircle.com/blog/email-hosting/dkim-selector-how-it-works-and-why-its-necessary/"}]}]
```

```json
{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://www.duocircle.com/"},{"@type":"ListItem","position":2,"name":"Blog","item":"https://www.duocircle.com/blog/"},{"@type":"ListItem","position":3,"name":"Email Hosting","item":"https://www.duocircle.comundefined"},{"@type":"ListItem","position":4,"name":"DKIM Selector: How It Works And Why It’s Necessary","item":"https://www.duocircle.com/blog/email-hosting/dkim-selector-how-it-works-and-why-its-necessary/"}]}
```

```json
{"@context":"https://schema.org","@type":"BlogPosting","headline":"DKIM Selector: How It Works And Why It’s Necessary","description":"One of the more popular and controversial email marketing techniques these days is DKIM.","url":"https://www.duocircle.com/blog/email-hosting/dkim-selector-how-it-works-and-why-its-necessary/","datePublished":"2022-07-13T21:01:19.000Z","dateModified":"2025-05-28T12:18:14.000Z","dateCreated":"2022-07-13T21:01:19.000Z","author":{"@type":"Person","@id":"https://www.duocircle.com/authors/brad-slavin/#person","name":"Brad Slavin","url":"https://www.duocircle.com/authors/brad-slavin/","jobTitle":"General Manager","description":"Brad Slavin runs DuoCircle, the company behind DMARC Report, AutoSPF, Phish Protection, and Mailhop. His focus is product strategy, customer relationships, and the commercial and compliance side of email authentication (DPAs, SLAs, enterprise procurement).","image":"https://media.mailhop.org/dmarcreport/images/team/brad-slavin.jpg","knowsAbout":["Email Security Strategy","SaaS Product Management","Enterprise Compliance","Customer Success","Email Deliverability Business"],"worksFor":{"@type":"Organization","name":"DuoCircle LLC","url":"https://www.duocircle.com"},"sameAs":["https://www.linkedin.com/in/bradslavin"]},"publisher":{"@type":"Organization","name":"DuoCircle LLC","url":"https://www.duocircle.com","logo":{"@type":"ImageObject","url":"https://www.duocircle.com/images/duocircle-logo.png"},"description":"DuoCircle is a portfolio of specialized email products covering protection, authentication, delivery, and routing. We deliver about 90% of category-leader capability at roughly half the price, backed by experts who own the outcome. Trusted by 50,000+ organizations since 2014.","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"}]},"mainEntityOfPage":{"@type":"WebPage","@id":"https://www.duocircle.com/blog/email-hosting/dkim-selector-how-it-works-and-why-its-necessary/"},"articleSection":"email-hosting","keywords":"","wordCount":719,"image":{"@type":"ImageObject","url":"https://media.mailhop.org/duocircle/images/2022/07/dmarc-report-7565.jpg","caption":"DomainKeys Identified Mail","width":900,"height":600},"speakable":{"@type":"SpeakableSpecification","cssSelector":[".answer-block","h1"]}}
```