Litmus pre-send testing Previews checklist guide

Use the Previews & QA section to view the results of your Litmus Test, an automated pre-send checklist of your email, and gain confidence before you send it. The Litmus Test makes sure every email you send is error-free.  With pre-send testing in Litmus, you can preview your email in 100+ apps and devices, validate your links, images, and tracking, test your email's load time, run spam tests, confirm emails are accessible to every subscriber, and more—all before pressing send.

Note: This pre-send testing checklist used to be called Litmus Checklist and was a stand-alone tool. Checklist is now labeled Previews & QA and is integrated into the email views with Summary, Builder, Proof, and Analytics. 

Previews tab screenshot showing Checklist Sections in the left menu

Start by sending or creating an email in Litmus 

To get started with a Litmus test you first need to create a new email by sending in or uploading your email. This detailed guide covers Creating an email in Litmus. Briefly, the options are:

  • Send an email draft from your ESP to your personal Litmus email address.  This will put the email into the Unsorted Emails view.
  • Sync from your ESP (available on Plus and Enterprise only).  This option also sends into Litmus but uses an API connection to do so.
  • Paste your HTML into Builder
  • Send your HTML from Builder via the Update Previews & QA or Update Proof & Previews tabs option depending on your subscription
  • Import an HTML file from a file sharing service like Dropbox, Google Drive, or OneDrive

Note: We recommend you send a draft email in or Sync from ESP for the most accurate previews and results.

Quick Start

  1. Navigate to any folder in Litmus
  2. Select New Email
  3. Enter a title and select Send or import your email from the Test workflow option.
    Screenshot of create a new email window with three workflows of Build, Test, and Review
  4. Choose an option to send in your email to your custom Litmus test address or sync from your ESP.
    Screenshot of steps to start a new test and button to copy your Litmus test address

Navigating the pre-send testing checklist

Select the Previews & QA tab to view your Litmus Test results. There are eight sections, starting with Previews. Scroll through the entire Litmus Test or use the sidebar to jump to a specific section. If we found an issue, we will highlight that in the left menu headings with indicators showing the number of warnings.

Screenshot of Litmus Previews & QA tab section


The first section you’ll see is your Email Previews. Similar to Builder, you can test your email across your selected email clients to help you find and correct rendering issues before you send your campaign. You can choose Grid view or Full-length previews to see a larger view.  

When your email is created, the previews in this section will be generated using your default client list. If you created the email, you can adjust which clients are previewed in a given email using the Choose email clients button.

Note: If the email was created by another user or sent with another user's unique test address, you will not be able to edit client selections.

Use the filters at the top to quickly jump to a specific preview or to sort the previews by popularity.  The popularity sort will use the last 180 days of your data from Litmus Email Analytics to sort the previews in order most opened by your subscribers. You can apply a filter to show any flagged previews you have selected during your review.

Previews filter options with data entry box, a dropdown to select three pre-set options, the flag filter icon, and grid or full-length toggle options

If a preview needs further attention, select the flag available in the lower right corner of each preview thumbnail. Choose a preview directly to see it in full screen view.

When in the full screen view, there is a Comparison View option in the upper right corner so you can look at previews side by side. You can toggle between the Comparison View and the Detail View as needed. There is an Edit Code button in the lower right corner of both views that will open a new Builder view so you can inspect and edit the code.

The lower right bar also includes a Toggle images off button for some email clients to see how your email will look with images off and a Recapture image option to refresh the preview.

First Impressions

In First Impressions, you’ll find checks for your Subject Line, From Name, Reply-to address, and Preview text. If we detect any errors in these categories, we'll suggest a fix for you. Otherwise, you'll see a green checkmark.


The Accessibility section will identify any areas of code that need attention and provide line numbers to help locate Alt-Text, Headings, Text Justification, and your table tags for the table role check. You'll find guidance on how to fix your HTML to create more accessible emails for all subscribers.

Litmus is the only platform that allows you to listen to an audio recording of your email and download a transcript to understand how a screen reader would relay it to a subscriber using that assistive technology.


We'll also check to make sure your links are working correctly. You'll be able to see your link text and path for each URL. Our check is comprehensive and includes a visual preview of the link, running the link against the Google Safe Browsing database to check for suspected phishing and malware pages, and verifying that click-throughs are being tracked. We’ll even expose Google Analytics UTM parameters if you’re using them on links in your email.

Tracking Check

The Tracking Check section will ensure that your clickthroughs are being tracked by your ESP and/or Google Analytics. We'll also let you know if a Litmus tracking code was included in your email.

Image Blocking Check

With so many email clients blocking images by default, and some subscribers choosing those settings on their own, image blocking is unavoidable. Luckily, you can earn a competitive edge in the inbox by using techniques like alt text and background colors so your email can remain legible in all circumstances.

Loading Speed Check

Loading Speed Check will show you how many images are in your email, the total size of all of the images included in your email, and of course, the total time it takes for all the images in your email to load. You can also see the size of each individual image and how long each took to load. We’ll also identify any broken images with a red X and you can click through to see each one.

Spam Testing

If you send an email into Litmus or use the ESP sync option to start your pre-send email test, then Litmus will automatically run a set of Spam tests. 

Spam testing checklist segment showing items to review and items passed

Note about Spam tests: If you have pasted the HTML or sent from Builder to Previews & QA via the Update Previews & QA or Update Proof & Previews tabs option depending on your subscription, we can't run spam tests. Spam tests are dependent on the sending domain for accurate results. You'll be prompted to start a spam test below the Spam Testing section of your checklist.

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