Every email client has an option to view the **headers** of a message or, in other words, the **source code of the email**. Headers are essential to diagnose delivery problems or to find out why an email was flagged as SPAM.

Below we explain how to view them depending on the email client you use.

## Roundcube

Open the message, expand the **"More"** menu and click **"Show source"**.

![Viewing headers in Roundcube](/api/help/media/8c9141c0-9d37-44fe-b7bb-e07be75b57f5)

## Horde

Open the message, expand the **"Other options"** menu and click **"View source"**.

![Viewing headers in Horde](/api/help/media/fe0dc868-97c2-48b7-a0b0-eb61f98f39ee)

## Gmail

Expand the email options (three-dot icon) and click **"Show original"**.

![Viewing headers in Gmail](/api/help/media/a000f0dd-a46b-4dfa-bd22-f47592eb604c)

## Hotmail / Outlook

Expand the **"Actions"** menu and click **"View message source"**.

![Viewing headers in Outlook](/api/help/media/ec3084a9-65a1-43dc-b0ed-188ac4067dfd)

## Yahoo

Expand the **"More"** menu and click **"View raw message"**.

![Viewing headers in Yahoo](/api/help/media/7e54b9e6-9aa6-4bde-878a-7e77a4f607be)

:::tip
If you are looking at the headers to understand why an email was flagged as SPAM, also check the guide [Emails received as SPAM](../hosting/email-recibido-spam).
:::