Introduction

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What is a domain?

A domain is the part of an email address that comes after the @ symbol. For example, in hello@acme.com, the domain is acme.com. When you send emails through SendKit, you need to prove that you own the domain you’re sending from. This process is called domain verification. It prevents anyone from sending emails pretending to be you.

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Why do you need to verify a domain?

Email providers like Gmail, Outlook, and Yahoo don’t trust emails by default. They check whether the sender is authorized to use the domain in the “From” address. Without verification, your emails are likely to end up in spam — or be rejected entirely. When you verify a domain in SendKit, you add DNS records that tell the world:

1. “SendKit is allowed to send emails for this domain” — this is what SPF does
2. “These emails really came from us and haven’t been tampered with” — this is what DKIM does
3. “Here’s what to do with emails that fail these checks” — this is what DMARC does

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DNS records explained

DNS (Domain Name System) is like a phonebook for the internet. It translates domain names into instructions that computers can understand. When you verify a domain, you’re adding entries to this phonebook that vouch for SendKit as a legitimate sender. SendKit generates 4 DNS records for each domain:

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SPF (Sender Policy Framework)

SPF is a TXT record that lists which mail servers are authorized to send emails for your domain. When a recipient’s mail server receives an email from your domain, it checks the SPF record to see if the sending server is on the list. Without SPF, anyone could send emails claiming to be from your domain.

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DKIM (DomainKeys Identified Mail)

DKIM adds a digital signature to every email you send. The recipient’s mail server uses a public key (published in your DNS) to verify that the email content hasn’t been changed in transit. Think of it like a wax seal on a letter — it proves the message is authentic and hasn’t been opened.

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MX (Mail Exchange)

The MX record on the send subdomain tells mail servers where to deliver bounce notifications and complaint feedback. This is how SendKit knows when an email bounces or when a recipient marks your email as spam.

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DMARC (Domain-based Message Authentication, Reporting, and Conformance)

DMARC ties SPF and DKIM together and tells receiving servers what to do when an email fails authentication. It’s optional for verification, but strongly recommended. Learn more in the DMARC guide.

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Domain verification in SendKit

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Verification statuses

SendKit automatically checks pending domains on a schedule:

• First 2 hours — every 10 minutes
• 2–12 hours — every 30 minutes
• 12–72 hours — every 60 minutes

After 72 hours, automatic checks stop. You can always verify manually.

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Subdomains

You can verify a subdomain instead of your root domain. For example, mail.acme.com or notifications.acme.com. This is useful if:

• You want to separate transactional emails from marketing emails
• You already have SPF/DKIM configured on your root domain for another service
• You want to isolate sender reputation between different types of email

Each subdomain has its own DNS records, verification status, and sender reputation.

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Next steps