> For the complete documentation index, see [llms.txt](https://docs.mailtrap.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.mailtrap.io/email-sandbox/testing/device-previews.md).

# Device Previews

Preview on Devices renders any captured email across a catalog of real email clients and devices - Gmail, Outlook, Apple Mail, mobile clients, and more.

**Device Previews** renders any HTML email captured in Email Sandbox across a catalog of real email clients and devices. The catalog contains more than 100 mobile, desktop, and web configurations, including Gmail, Outlook, Apple Mail, mobile clients, and available light- and dark-mode variants.

Choose the clients you want to test and start the preview. Mailtrap returns a screenshot for each successfully rendered configuration and shows results progressively. This way, you can check how the email will look before sending it to recipients.

<figure><img src="https://1476453098-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FS3xyr7ba7aGO19rc8dSK%2Fuploads%2FgeCi9c03KaN38sdMV9pB%2Fdevice%20previews%201.png?alt=media&amp;token=600f87da-61ed-41f0-955e-b94b08e2b804" alt="" width="375"><figcaption><p><em>Review screenshots from selected email clients in the Device Previews tab.</em></p></figcaption></figure>

{% hint style="info" %}
Device Previews produces screenshots for visual review. Use **HTML Check** for HTML/CSS compatibility and **Spam Analysis** for spam-related checks.
{% endhint %}

### Availability and access

Device Previews is available as a paid add-on on the **Business** and **Enterprise** [Email Sandbox plans](https://mailtrap.io/pricing/?tab=email-sandbox).

If your account is eligible, open **Device Previews** and click **Request Add-on**. Our customer support team will then confirm the commercial terms and enable the add-on for your account.

<figure><img src="https://1476453098-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FS3xyr7ba7aGO19rc8dSK%2Fuploads%2FXuZMu6htBzQWcGqhtGfM%2Ftest%20test%20email.png?alt=media&amp;token=98e76c24-6c4b-4fae-a301-1c7c51ffa2f4" alt=""><figcaption><p><em>Request the add-on from the Device Previews tab.</em></p></figcaption></figure>

### How to create Device Previews

* Open **Email Sandboxes**.
* Select **Projects**, open a Sandbox, and select a message with an HTML body.
  * Plain-text-only messages do not have the Device Previews tab
* Select the **Device Previews** tab and click **Test on Devices**.

<figure><img src="https://1476453098-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FS3xyr7ba7aGO19rc8dSK%2Fuploads%2FILyfdaIEjN6hY0KTGZJk%2Ftest%20on%20devices.png?alt=media&amp;token=5f5fe67f-ab59-48df-ac13-4ad3fcc09b06" alt=""><figcaption><p><em>Start from an HTML message in Sandbox</em></p></figcaption></figure>

* In **Clients and devices**, browse **Mobile**, **Desktop**, and **Web**, and select the configurations to test (select light- and dark-mode variants separately when both are available).
* Click **Preview on N devices**.

<figure><img src="https://1476453098-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FS3xyr7ba7aGO19rc8dSK%2Fuploads%2FOH1Srl3ZFFSsFSRsjiRS%2Fpreview.png?alt=media&amp;token=d9bdff69-304b-4b62-9a98-c62f1717ca7d" alt=""><figcaption><p><em>Choose the client configurations relevant to your recipients.</em></p></figcaption></figure>

{% hint style="info" %}
Check the usage message at the bottom of the drawer. For example, '**8 previews will be used**' means the test consumes eight previews.
{% endhint %}

Mailtrap will then render your previews and show client results as they become available.

<figure><img src="https://1476453098-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FS3xyr7ba7aGO19rc8dSK%2Fuploads%2F3GYB4XSlKPWpZZvUpEiH%2Fpreview%202.png?alt=media&amp;token=8d5b2b7c-5bb8-46a5-9aa3-2226c26c823f" alt=""><figcaption><p><em>Choose the client configurations relevant to your recipients.</em></p></figcaption></figure>

{% hint style="warning" %}
One captured message supports one Device Previews test. You cannot add clients after submitting it. To test changed HTML or another selection, send a new message to Sandbox.
{% endhint %}

### Review and re-render previews

Mailtrap returns a screenshot for each successfully rendered configuration and shows results progressively. However, keep in mind that completed results can appear while other clients are still rendering, and some clients may take longer.

#### Open a completed preview

* Hover over a completed tile and click **Preview**.

<figure><img src="https://1476453098-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FS3xyr7ba7aGO19rc8dSK%2Fuploads%2FGXdjDLkIBGM81NZxKLfD%2Fclick.png?alt=media&amp;token=2060d06c-3785-44d5-b2b4-1c933ed2baf3" alt="" width="563"><figcaption></figcaption></figure>

* Inspect the email in fullscreen. Check layout width, stacking, text wrapping, fonts, spacing, images, buttons, backgrounds, dark-mode transformations, and footer content.

<figure><img src="https://1476453098-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FS3xyr7ba7aGO19rc8dSK%2Fuploads%2FQr61jZeg2SrQHyRIGKj7%2Frendered.png?alt=media&amp;token=6c79eeb6-d557-4991-adeb-705ab259c86b" alt="" width="563"><figcaption><p><em>Inspect completed results in fullscreen.</em></p></figcaption></figure>

Close fullscreen to return to the results grid. The selector contains completed results only.

#### Re-render a completed preview

Use Re-render to request a fresh screenshot of the same captured HTML for a completed result.

* Open the completed result in fullscreen.
* Click **Re-render**.
* Confirm the client in **Re-render this preview?**
* Click **Re-render**.

The action does not use another preview. It uses the same captured HTML; send a new message if the source changed.

<figure><img src="https://1476453098-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FS3xyr7ba7aGO19rc8dSK%2Fuploads%2FlfAbMPZv8jnP37vpXVwf%2Fre-render.png?alt=media&amp;token=5a70817f-a022-4931-9e37-b5384e002bcf" alt=""><figcaption><p><em>Confirm the client before requesting a fresh screenshot.</em></p></figcaption></figure>

{% hint style="warning" %}
A **Couldn’t render preview** tile cannot be opened or re-rendered. If the client is required, capture a new message and run another test, or contact Support if the same client repeatedly fails.
{% endhint %}

### Preview templates, campaigns, and automation emails

* Open the template, campaign, or automation email.
* Click **Send Test**.

<figure><img src="https://1476453098-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FS3xyr7ba7aGO19rc8dSK%2Fuploads%2FtFzRN7xcneBoUhouCz8q%2Ftemplate%201.png?alt=media&amp;token=66f75743-9438-4080-a824-6d4a3604a00b" alt=""><figcaption></figcaption></figure>

* Select **Device Previews**, an active Sandbox, and click **Send Email to Sandbox**.

<figure><img src="https://1476453098-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FS3xyr7ba7aGO19rc8dSK%2Fuploads%2F66sdpZItRD4yFpLMyEoo%2Ftemplate%202.png?alt=media&amp;token=910d35e3-543c-4233-ae3a-74bbc84e9aec" alt=""><figcaption></figcaption></figure>

* Mailtrap creates the message and opens its **Device Previews** tab.

{% hint style="warning" %}
The send uses the regular Sandbox email quota and rate limit. The selected configurations use the separate Device Previews allowance.
{% endhint %}

### Usage and limits

A **test** belongs to one captured message. A **preview** is one selected client configuration and its screenshot:

* One selected configuration uses one preview.
* Selecting eight configurations uses eight previews.
* Separate light- and dark-mode selections count separately.

After the add-on is enabled, the tab header shows **Previews used: X / Y. X** is the number used in the current period, and **Y** is the account’s allowance. The **Sandboxes usage** card also shows the count under **Email previews**.

When all previews are used:

* **Test on Devices** is disabled for messages without results.
* A banner shows **You’ve used all your previews**.
* The banner shows the reset date when available, or says the allowance resets at the next billing period.
* Clicking on **Contact Support** opens a request for additional previews.

If a selection exceeds the remaining allowance, reduce the number of configurations and submit again.

<figure><img src="https://1476453098-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FS3xyr7ba7aGO19rc8dSK%2Fuploads%2FVXYVh3AfvLFKVU469NLd%2Flimit%20reached.png?alt=media&amp;token=fd5d5d06-c1f5-45a4-9075-68ef3334d9c9" alt=""><figcaption><p><em>Wait for the reset or contact Support about additional previews.</em></p></figcaption></figure>

### Troubleshooting

| Device Previews tab is missing             | The message has no HTML body                                           | Send an HTML message and open the new capture                                                            |
| ------------------------------------------ | ---------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------- |
| The page shows **Upgrade**                 | The account is on an ineligible plan                                   | Upgrade to a Business or Enterprise Email Sandbox plan                                                   |
| The page shows **Request Add-on**          | Eligible plan, add-on not enabled                                      | Request activation from Support                                                                          |
| Test on Devices is disabled                | Monthly allowance is exhausted                                         | Wait for the displayed reset or contact Support                                                          |
| Selection is rejected                      | Selection exceeds remaining usage, or the catalog changed              | Reduce the selection; reopen the drawer if needed                                                        |
| Some clients keep processing               | Clients complete independently                                         | Check again later; contact Support if required clients remain stuck                                      |
| **Couldn’t render preview**                | That client did not return a screenshot                                | Use a new message/test; contact Support if it repeats                                                    |
| Completed result looks incomplete          | Source HTML, external assets, or client support differs                | Check the captured HTML, public assets, and HTML Check; re-render only if a remote asset may have failed |
| Device Previews is temporarily unavailable | Request or result service failed                                       | Try later; contact Support with account, Sandbox, message, time, and failed action                       |
| **Send Email to Sandbox** fails            | Sandbox inactive, Sandbox email quota/rate limit, or invalid test data | Fix the Sandbox sending error and send again                                                             |
| Old previews disappeared                   | Retention ended or the message was removed                             | Capture a new message and run a new test                                                                 |


---

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