> ## Documentation Index
> Fetch the complete documentation index at: https://jetemail.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# 550 [DKIM] Block

> DKIM validation failed due to missing required DKIM CNAME record

### Introduction

This error occurs when your domain is missing the required DKIM CNAME record for JetEmail to sign your outbound mail.

### Example Error Message

Here's what this error can look like:

```
550 DKIM validation failed: Required CNAME record jetemail._domainkey.domain.com not found.
```

### What is DKIM?

DKIM (DomainKeys Identified Mail) attaches a cryptographic signature to each email so recipients can verify that the message was authorized by your domain and wasn't altered in transit.

### Why You’re Seeing This

* Your domain has not published the required DKIM CNAME used by JetEmail to sign messages on your behalf; or
* You are relaying through a smarthost and your upstream system is not DKIM-signing messages (or the signature is being removed), causing our service to require your DKIM CNAME instead.

### How to Fix

If you want JetEmail to DKIM-sign your messages, publish this CNAME in your DNS:

```
Name: dkim._domainkey.{your-domain}
Value: dkim.jetsmtp.net
```

Replace `{your-domain}` with your actual domain. Example:

```
dkim._domainkey.example.com CNAME dkim.jetsmtp.net
```

If you relay through a smarthost and already DKIM-sign mail upstream, you should not see this error. If you do, your messages are not being DKIM-signed (or the signature isn’t preserved). Ensure your MTA is signing outbound mail correctly, or alternatively publish the CNAME above so JetEmail can sign.

### Verification

* Allow up to 24 hours for DNS propagation
* Verify your DKIM setup with your preferred DNS/DKIM checker
* Retry sending once DNS has updated

For broader setup details, see our [Email Authentication Requirements](/outbound/email-authentication) and [DMARC](/outbound/dmarc) guidance.