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# 550 [MX_INVALID]

> Email rejected due to missing MX record for sending domain

### Introduction

This error occurs when attempting to send email through JetEmail's SMTP servers from a domain that does not have valid MX (Mail Exchanger) records configured in its DNS settings. Missing MX records indicate that the domain is not properly configured to receive email, which is often a sign of an unauthorized or improperly configured sending domain.

### Example Error Message

Here's what this error looks like:

```
user@example.com
   host relay.jetsmtp.net [103.173.0.0]
   SMTP error from remote mail server after end of data:
   550 [MX_INVALID] Blocked. See https://reports.jetsmtp.net/?id=000000000000000000&auth=smtpuser
```

### What is an MX Record?

An MX (Mail Exchanger) record is a DNS record that specifies which mail servers are responsible for receiving email on behalf of your domain. Valid MX records are essential for email deliverability and are considered a basic requirement for legitimate email sending domains.

### How to Fix This Error

1. Log into your domain's DNS settings
2. Add an MX record for your domain
3. The record should point to your mail server, for example:
   ```
   example.com.    IN    MX    10    mail.example.com.
   ```
4. If you use a third-party email provider, they will provide the correct MX records to use

### Verification

After adding the MX record:

* Allow up to 24 hours for DNS propagation
* You can verify your MX records using [MXToolbox](https://mxtoolbox.com/SuperTool.aspx) or similar DNS checking services
* Try sending your email again once DNS has updated