{"id":4360,"date":"2017-04-13T00:00:00","date_gmt":"2017-04-13T00:00:00","guid":{"rendered":"https:\/\/www.litmus.com\/blog\/why-is-email-rendering-so-complex\/"},"modified":"2025-12-23T17:20:04","modified_gmt":"2025-12-23T22:20:04","slug":"why-is-email-rendering-so-complex","status":"publish","type":"post","link":"https:\/\/www.litmus.com\/blog\/why-is-email-rendering-so-complex","title":{"rendered":"Why is email rendering so complex?"},"content":{"rendered":"\n\n\t
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Editor’s note<\/strong>: Email rendering has grown in complexity since this article was first published. Chad has since shared an updated view<\/a> of the different potential renderings a single email might have, including that there are more than 300,000 potential renderings for an email.<\/p>\n

A print campaign has one rendering. Website rendering is significantly more complex, since sites can look different depending on a device\u2019s operating system, browser, and screen size. But even that is no match for the complexity of email rendering.<\/p>\n

In addition to OS, browser, and screen size, the email marketing platform the brand uses, the subscriber\u2019s email client, and whether images are enabled or blocked dramatically affect email rendering. If we bundle webmail clients together with browsers, there are five major factors that determine how an email renders:<\/p>\n

    \n
  1. Email service providers (ESP)<\/li>\n
  2. Operating systems<\/li>\n
  3. App and web-based email clients<\/li>\n
  4. Screen sizes<\/li>\n
  5. Images enabled\/blocked<\/li>\n<\/ol>\n

    Let\u2019s look at each of these layers.<\/p>\n

    Email Service Providers<\/h2>\n

    Before you send your email, your ESP can change your email\u2019s code. In addition to adding tracking pixels and redirecting links for tracking purposes, your email marketing platform may strip out certain parts of code.<\/p>\n

    This is generally for your benefit. For instance, they remove code that may get your emails caught in content filters, resulting in deliverability issues. However, some of these changes may harm the rendering or functionality of your emails\u2014which is why Litmus always recommends previewing emails in Checklist before you send from your ESP.<\/p>\n

    Be extra mindful of this fact if you’ve recently changed ESPs or plan to. Your emails may have been rendering fine, but your new email platform may cause some of your emails to break.<\/p>\n

    \n\n\n\n
    \"\"<\/td>\n\n

    Preview your emails with Litmus Checklist<\/h2>\n

    Preview emails with images-off and get notified if any of your images are missing ALT text with Litmus.<\/p>\n

    BOOK A DEMO \u2192<\/a><\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

    Depending on how you define an email service provider, you could say there are upwards of 400 email marketing tools. But let\u2019s assume there are approximately 150 ESPs of reasonable scale.<\/p>\n

    That said, we\u2019re talking about how your emails render and you don\u2019t use that many ESPs. On average, brands use 1.8 email marketing platforms to send their marketing emails. For the sake of easier math, let\u2019s round that up to an even 2.<\/p>\n

    \"Number-of-email-platforms-used-chart-01\"<\/figure>\n

    [Tweet this chart \u2192]<\/a><\/p>\n

    Operating Systems<\/h2>\n

    The OS of your subscriber\u2019s computer, tablet, smartphone, or other device limits or enhances the capabilities of the email client that sits on top of it. While a handful of major OSs dominate the market, many different versions of those OSs are in use by consumers. For instance, Windows 10, 8, and 7 all have considerable market share.<\/p>\n

    Across the major desktop and mobile operating systems including Windows, OS X, Android, and iOS, let\u2019s say there are about 15 OS versions of reasonable scale.<\/p>\n

    App and Web-based Email Clients<\/h2>\n

    The email client is the heart of email rendering. Email clients can run in desktop, mobile, and web environments. Web-based email clients have an extra layer of complexity because they render differently in different browsers. For example, Gmail functions a little differently depending on whether a subscriber is using Chrome, Firefox, Internet Explorer, or Safari.<\/p>\n

    Litmus has identified about 1,000 webmail clients around the world, plus roughly 250 mobile email apps, along with a much smaller number of desktop email apps. Litmus Email Previews<\/a> currently supports more than 70 different email apps and webmail-browser combinations, and that number is growing.<\/p>\n

    Ignoring the email clients with the smallest market share and including the necessary webmail-browser combos, let\u2019s assume that every brand should be concerned about approximately 50 email clients that have reasonable scale in their markets.<\/p>\n

    Screen Size<\/h2>\n

    The size of the subscriber\u2019s screen or monitor also has a big impact on email rendering. Interacting with an email on a 21-inch monitor and a smartphone with a 4-inch screen are dramatically different experiences.<\/p>\n

    In the smartphone category alone, there are hundreds of unique screen dimensions. To simplify things, let\u2019s assume there are just 5 screen size categories that we care about: desktop, laptop, tablet, phablet (ph<\/u>one-tablet<\/u> hybrids), and smartphone.<\/p>\n

    Images On\/Off<\/h2>\n

    Lastly, images can be enabled and blocked<\/a> in many email clients. This generally creates two very different renderings of an email\u2014sometimes wildly different renderings.<\/p>\n

    \"Anthropologie<\/a><\/figure>\n

    So let\u2019s double the number of email rendering possibilities.<\/p>\n

    The Grand Total<\/h1>\n

    If we put all those factors together, we get\u2026<\/p>\n

    2 email service providers x 15 operating systems x 50 email clients x 5 screen sizes x 2 image states =<\/p>\n

    Every email that marketers send has approximately 15,000 potential renderings (and that\u2019s using conservative math).
    \n[Tweet this \u2192]<\/a><\/p><\/blockquote>\n

    Plus, that\u2019s ignoring instances where an email client doesn\u2019t support HTML and displays the plain-text version<\/a> or watch-html version<\/a> of the email instead, and instances when a screen reader is used<\/a>.<\/p>\n

    Some might view that as an argument for sending more plain-text emails. However, HTML emails have generally proven to be much more effective. So, this exercise in rendering permutations is simply a reminder that rigorous testing should be a part of every brand\u2019s email workflow.<\/p>\n

    \n\n\n\n
    \"\"<\/td>\n\n

    Create Great Customer Experiences<\/h2>\n

    Preview your emails in 100+ email clients, toggle between desktop and mobile views, turn images on and off, and more to ensure that your emails are generating the best customer experiences possible.<\/p>\n

    BOOK A DEMO \u2192<\/a><\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n \t\t\t<\/div>\n \t\t<\/div>\n \t<\/div>\n <\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

    The marketer’s email service provider and the subscriber’s operating system, browser, email client, screen size, and whether they’ve enabled images all affect email rendering. All of these layers of complexity add up to the possibility of more than 10,000 different email renderings for every email you send.<\/p>\n","protected":false},"author":3,"featured_media":4361,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"tags":[468,1575],"blog_category":[57],"class_list":["post-4360","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","tag-images","tag-rendering","blog_category-observations"],"yoast_head":"\nWhy is email rendering so complex? - Litmus<\/title>\n<meta name=\"description\" content=\"The marketer's email service provider and the subscriber's operating system, browser, email client, screen size, and whether they've enabled images all affect email rendering. All of these layers of complexity add up to the possibility of more than 10,000 different email renderings for every email you send.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.litmus.com\/blog\/why-is-email-rendering-so-complex\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Why is email rendering so complex?\" \/>\n<meta property=\"og:description\" content=\"The marketer's email service provider and the subscriber's operating system, browser, email client, screen size, and whether they've enabled images all affect email rendering. All of these layers of complexity add up to the possibility of more than 10,000 different email renderings for every email you send.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.litmus.com\/blog\/why-is-email-rendering-so-complex\" \/>\n<meta property=\"og:site_name\" content=\"Litmus\" \/>\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/litmusapp\" \/>\n<meta property=\"article:published_time\" content=\"2017-04-13T00:00:00+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2025-12-23T22:20:04+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.litmus.com\/wp-content\/uploads\/2020\/04\/why-is-email-rendering-so-complex.png\" \/>\n\t<meta property=\"og:image:width\" content=\"1380\" \/>\n\t<meta property=\"og:image:height\" content=\"724\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/png\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:creator\" content=\"@litmusapp\" \/>\n<meta name=\"twitter:site\" content=\"@litmusapp\" \/>\n<!-- \/ Yoast SEO Premium plugin. -->","yoast_head_json":{"title":"Why is email rendering so complex? - Litmus","description":"The marketer's email service provider and the subscriber's operating system, browser, email client, screen size, and whether they've enabled images all affect email rendering. 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