Litmus Previews & QA pre-send testing guide

The Previews & QA section in Litmus lets you view the results of your tests and provides an automated pre-send checklist of your email. You can check your email in 100+ different previews, validate your links, images, and tracking, test your email's load time, run spam tests, confirm emails are accessible to your subscribers, and more—all before pressing send.

previews & qa tab with left menu checklist sections

Create or send in an email to Litmus 

Create a new email by sending in or uploading your email.

  • 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

Previews & QA checklist sections

Your pre-send checklist has multiple sections with a link in the left menu to each. If any alerts are found, you'll see an indicator with a number that shows how many items need attention. Scroll through the entire checklist or select a section link to jump directly to any point.

animation of selecting the left menu checklist sections

Previews section

Similar to Builder, you can test your email across 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.  

The previews in this section will be generated using your default email 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. Each view has an Edit Code button in the lower toolbar that will open the Builder tab so you can inspect and edit the code. You can flag either preview in the comparison for review and can check Visual impairment filters on the comparison preview.

preview comparison view with arrow indicating flag icon and with visual impairment filter options expanded

Email Guardian

Introduced in September 2023, Email Guardian automatically scans your selected emails every 24 hours for email client changes that affect your content. Email Guardian notifies you of any major changes that might impact your subscribers' experience.

email guardian in the previews & qa checklist

First impressions section

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.

Accessibility section

The accessibility section includes our visual impairment filters, automatic accessibility checks in over 40 different categories, and our exclusive audio transcription using NVDA screen reader. Learn more about our Accessibility testing to reach as many subscribers as possible!

animation showing accessibility check section in previews & qa

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.

links section in previews & qa checklist showing status of links in an email project

You may have some cases where you do not want your link checked during our testing, such as an unsubscribe link that would unsubscribe your Litmus test email address.

We use logic to identify unsubscribe links to avoid activating them, but it relies heavily on being able to find the word unsubscribe in the link and in the <a> tag. If your <a> tag does not have this, add the word unsubscribe in both the link text and the <a> tag so the checker ignores them.

To prevent the system from testing other links or without adding unsubscribe to your links, you can add the attribute data-litmus-ignore instead. That attribute can be applied to any link you want the Link Checker to skip.


<a href="your_unsubscribe_link" data-litmus-ignore >Remove me from mailing list</a>

Tracking section

Litmus checks your marketing analytics in your links and the status of your Litmus email analytics tracking code if you've included one.

tracking section of previews & qa

Image blocking section

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.

image blocking preview of your email project

Loading speed section

The 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.

As with links, you can include the data-litmus-ignore attribute in your image tag to have Litmus ignore an image during the speed test.

loading speed section listing all images and their status

Spam testing section

Plus and Enterprise customers have access to spam testing. Send an email into Litmus with the included email address or use the ESP sync option to start your pre-send email test and automatically run a set of 8 essential spam checks (you'll also have the option to run a more extensive spam check if needed). 

Our Spam Testing in Previews and QA makes sure your authentication records are set up properly, including DMARC, DKIM and more, in addition to making sure you’re not on any blocklists. We now also verify you have BIMI set up and configured correctly.

spam test section showing custom spam test address

NOTE: If you have pasted your HTML or sent from Builder to Previews & QA via the update button option, we can't run spam tests. Spam tests are dependent on your 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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