Home Resources Blog

For the most recent results and tips, view our guide on Image Blocking in Email.

Since our last update to our ‘Image Blocking in Email Clients‘ guide in 2007, its come to our attention that a lot has changed. In fact, email clients are more aggressively blocking images by default than before, with a 2009 report stating that only 48% of email recipients see images automatically. This means that if an email campaign relies heavily on images, it’s probably not being read by over half of its intended recipients.

What this means for email designers is that we have to be prepared for images to be blocked automatically in our campaigns. In this post, we’ll look at current conditions for image blocking in email clients, as well as suggest new strategies for getting your message across, even if it’s image-free.

Default settings in popular email clients

As well as refreshing our original results, we’ve also covered current conditions across the most popular mobile email clients. For more information on how ALT tags display in these email clients, check out our most recent results.

Desktop clients Images displayed by default Images disp. for trusted senders Renders ALT Text
Outlook 2007 No Yes Replaces ALT text with security message
Outlook 2003 No Yes Yes
Outlook for Mac 2011 No Yes Yes
Outlook Express Yes No Yes
Windows Live Hotmail No Yes Yes
Apple Mail Yes No No
Thunderbird No Yes Yes
AOL Desktop No Yes No
Lotus Notes Yes Yes Yes
Webmail clients Images displayed by default Images disp. for trusted senders Renders ALT Text
Hotmail No Yes No
Yahoo! Mail Beta No Only if changed in ‘Spam’ settings Yes
Gmail No Yes No
AOL Webmail No Yes Yes
Mobile clients Images displayed by default Images disp. for trusted senders Renders ALT Text
iPhone/iPad Yes Yes Yes
Android default No No Yes
Android Gmail No Can select ‘Always show pictures from this sender’ when images are displayed No
Windows Mobile 7 No No No
Blackberry OS6 No No Yes

As you can see from the above results, blocking images by default in email clients is the norm, not the exception as was previously thought. Webmail clients in particular have cracked down on the automatic display of images, most probably to prevent tracking images from being downloaded in spam email.

Surviving image blocking in 2011

In our earlier blog post, we provided some timeless advice for ensuring your message is displayed, even with images off. These pointers are more relevant than ever, as we ultimately have to anticipate our images being blocked in the inbox.

In addition to becoming a known sender, ensuring that your images come with ALT text and using text as much as possible throughout your designs, there are some creative solutions to consider when designing for image blocking. Here are two of our favorites.

Style up your ALT text

Now you’ve got your ALT text in place, how about making it a little fancy? Funnily enough, you can style up your ALT text using CSS, just as you would any other text in your HTML email. Here’s an example of an email in Yahoo! Mail Beta with a plain-jane ALT tag:

ALT text without styles

How about if we want to make it look more like the heading? More like:

ALT text with styles

Here’s the code we used to achieve this:

<img src="https://www.campaignmonitor.com/assets/uploads/pizza.jpg" alt="Try our Bacon Lover's Pizza" width="220" height="200" style="color: #C30; font-weight: bold; font-size: 16px;"/>

A tip is to explicitly set the width and height of images with ALT text to prevent them from collapsing. This technique works in Yahoo! Mail, iPhone, Gmail, Apple Mail and Thunderbird. In Outlook Express, you can only change the color.

Another example and more details can be found here.

Substitute images with HTML/CSS

Perhaps one of the most creative approaches we’ve seen when it comes to tackling image blocking can be found in this amazing email for Pizza Express. Thanks to a table layout and some meticulous image cutting, this design substitutes images for blocks of color, turning the email into a work of 8-bit wonder when images are turned off (click to enlarge):

Pizza Express image substitution

Thanks to Andrew King for this excellent example. To view some more email newsletters that have used a similar technique to do away with images, I highly recommend you scoot over to Anna Yeaman’s blog post on how to bypass image blocking by converting images to HTML. She’s famously used her pixel-art and coding skills to send totally imageless HTML email campaigns, although you wouldn’t know it at first glance (click to view):

On a closing note, image blocking is something that we all have to take seriously as email designers. Sending all-image HTML email campaigns may have worked in the past, but at a time when so many email clients do not display images by default, it’s likely that they will either not display in most preview panes, or simply get junked/deleted.

The good news is that there are both practical and highly creative approaches you can take to this issue, most of which are easy to implement. If you have a favorite technique for ensuring your message gets displayed in any inbox, we’d love to hear about it in the comments below.

  • salvador

    External images, and what about inline images ?
    For example, Gmail always show inline images from trusted or not trusted senders.

  • Thilo Hermann

    What about Thunderbird? I always thought that remote images are being blocked there by default? Or is it just my settings? (using Thunderbird for ages…)

  • Shannon Mølhave

    In my Android Gmail app it doesn’t automatically display images from people in my contacts, but it does give me the option to “Show pictures” and then “Always show pictures from this sender”, which is kinda like the trusted sender thing.

  • igor Griffiths

    Thanks for the heads up, I have just changed autoresponder service and they mock the use of plain text messages, which I have always used for my newsletters.

    Looks like my instinct was correct, going to stick, as GetResponse puts it, back in the 80’s.

    igor 8)

  • Jarrod

    Hey Ros, nice article. I currently do this and you can actually make some nice looking emails when images are blocked.

    My understanding of how open rates are measured is that when a recipient opens an email, an image is downloaded and that is marked as an open. If our average open rate is 40%, we can safely assume that 40% of our customers are viewing the emails with images shown – right?

  • Ros Hodgekiss

    @salvador – By inline, do you mean embedded images? Let me know and I’ll look into this for you.

    @Thilo – You’re so correct – Thunderbird doesn’t display images by default. I’m sorry about that and have fixed up the results above. Thanks for pointing that out!

    @Shannon – Ah, that’s good to keep in mind! Off the bat I didn’t see that option, but I’ve now updated the results to reflect this.

    @igor – There are legitimate reasons to stick to plain text, however it does mean that you miss out on tracking of opens. Have you considered providing a solid plain-text alternative to your HTML email content?

    @Jarrod – I wish it was this straightforward, however if a trackable link in an email is clicked on when images haven’t been loaded, then an open is recorded for the email. We make mention of this here.

    For this reason, there’s a good chance that < 40% of your subscribers are displaying images by default, as if you’ve designed your email with images off in mind (as you’ve mentioned), then you’re probably receiving clicks that are in turn, being counted as opens. So keep up the good work with designing for image blocking! :)

  • Alex

    My god – that block/rendering version of an image seems like such a painful thing to have to code. Sounds like if you have to do that, your content should be more compelling to get users to form the habit of downloading your images.

  • Thomas Bacon

    I loved the clever email animated gif header image in the HTML email you sent about this blog post. (luckily I have messages from campaign monitor set always display images :) )

  • Kost

    Do you have stats on image blocking for images in email signatures, either linked or embedded? While the email itself is not distributed the same as an email campaign it would seem that the email rendering should conform to the same table listed above but I do not believe that is the case. In my experience some form of trusted rules apply.

    Images in signatures is a popular marketing practice and a comparison would come in handy.

  • Surfing Dogs

    THis statement “only 48% of email recipients see images automatically.” does not actually result in “This means that if an email campaign relies heavily on images, it’s probably not being read by over half of its intended recipients.” because presumably all your list are opt in subscribers so some of the 52% have marked you as “trusted sender” and others have changed the default settings. I would like to see some stats on how many users have changed their default settings to show images.

  • Jim

    What are peoples thoughts on using Return Path to ensure images are enabled in Yahoo and a few other email clients? How beneficial is paying for this service? Thoughts please!

  • CPL

    Great article. Does it matter whether I: 1) enclose an image in a ZIP file when I import the campaign into CM or 2) include a link to an external URL with the image?
    Which is better to ensure the image is being seen?

  • Ros Hodgekiss

    @Alex – Agree, that would be a lot of hard work. However, the results are pretty eye-catching, so props to the designers for giving it a try!

    @Thomas – Haha, glad you enjoyed it! The header image was a creation by Pete Usborne here, I tip my hat to him for trying something a little different :D

    @Kost – We don’t have any findings specifically on email signatures, I’m sorry to say. It’s probably true that sending one-to-one style emails would probably yield different results from sending via an email marketing service, but then again, you would be hard-pressed to send HTML email with the former method. Note that we haven’t had a lot of luck with embedding images in the past.

    @Surfing Dogs – First up, you have an amazing name. I want a surfing dog!
    But onto the serious stuff, you’re right – there will be exceptions. It would be fascinating to know how often subscribers mark email newsletters as being trusted or have changed their default settings, however as you can imagine, this information is hard to come by unless you’re somehow privy to the inner workings of an email client. We’ll keep our ears to the ground and pass on any information we find on this topic.

    @CPL – I don’t have comparative data either way, but would presume that the results would be the same. In both cases the images are being downloaded from a server somewhere. Uploading the image to Campaign Monitor does give you the advantage of using our CDN to serve images (ie. speed, reliability), however either method should yield the same results.

  • Terro

    I think Campaign Monitor should allow inlining of images in mails, optionally for a premium to make up for the increased bandwith requirements.

    @Ros – the linked post is from 2008 and is based on testing done even earlier, so I think CM should take a close look at where things stand today.

    It would be interesting to send a “click here”-image to some larger list with trusted and loyal users, to try to get an approximation of the number of users who have 1) disabled images but 2) whitelisted the mailing list address, and can see the link (optionally with A/B testing to compare the click % on the regular content, and the % on indentical contant that is only visible to some)

  • Markus

    Thanks for the very good overview. If you think Desktop Browers can be a tricky then head for email clients :)

  • Pedro Manacas

    Great article Ros.
    Regarding default settings in software there is at least anecdotal evidence that 90%+ of users never change them. See this amusing story about MS Word for example: http://www.uie.com/brainsparks/2011/09/14/do-users-change-their-settings/

  • Charlotte Coleman

    Really interesting article – the styled alt and the Pizza Express email have certainly given me some ideas. I imagine the Pizza Express emails actually encourages more people to download the images as I would be curious what the actual image looks like! Thanks

  • Ross

    The biggest problem as I see it is that some email clients don’t show ALT text. What on earth are we supposed to do with that!? I can cope with images not displaying by default otherwise.

    I have a client with 25% Hotmail subscribers, styling the ALT text isn’t going to help if it isn’t even seen. This is a big problem, mainly because the company logo/name and main headings are images.

    Perhaps you could do an article on email client support for web fonts?

    Any other ideas appreciated!

  • Ross

    Just found your article on @font-face, seems like that’s no solutions :-(

  • HappyTorso

    An interesting study would be testing recipients’ reactions to an image-only campaign (no alt texts).
    When a recipient opens an email and sees part of the information he might decide that he knows enough, but what happens when he opens an email and all of the information is hidden by the client’s default settings?
    Would curiosity win over habit?

  • Tony

    How do you get around the problem of Outlook putting missing image icons where the images should be, and forcing in the writing:

    “Right-click here to download pictures. To help protect your privacy, Outlook prevented automatic download of this picture from the Internet…”

    And pushing the ALT text completely out of view if the image is too small? How did the Pizza Express design above avoid this situation? What does it actually look like in Outlook? Not like it does here in this article, I suspect…

  • Adey


    That’s a good point. I wondering the same myself. After a little testing I got the best results in Gmail with a period in the alt text. It leaves little dots over the abstracted image but no broken image icon. However in Outlook 2003 you still see the broken image icons.

  • Andrew Kordek


    Great stuff. Can I get you to define a trusted sender? I assume you mean its only for senders that have been whitelisted by the subscriber right?

    Andrew Kordek
    Co-Founder, Trendline Interactive
    A Strategic Email Marketing Agency
    Twitter: @andrewkordek & @trendlinei
    Email: andrew@trendlineinteractive.com

  • Salvador

    @Ros Hodgekiss, yes i mean “cid:” nowadays it works great in most emails clients.
    (campaignmonitor should update the article about inline images :)
    Thanks, good job

  • Salvador

    Email structure to test cid: http://pastebin.com/FTSPysSc

  • Lars Weimar

    This article REALLY inspired and changed the way I look at email marketing.

    As a result, I recently re-designed a Newsletter that we send out to clients. I wanted to link you guys to it to see if you also wanted to put it on your design gallery.

    The goal was to make everything important to be viewable without images…even the call to action. I also wanted lots of color to be able to be seen without images, as well. It degrades gracefully for Outlook but the online version is loaded with more current CSS techniques (which also work in Gmail and other more advanced email clients). Would love any feedback, too! :)



  • MondoVox

    Does this also mean that the open rates are limited to the 48% who can view images automatically? Pretty much or thereabouts kinda thing? Thinking this further obfuscates a true open rate.

  • Ros Hodgekiss

    Hi MondoVox, there isn’t such a thing as a ‘true open rate’, from any service. Open rates are based on what’s measurable and there will always be instances when opens cannot be measured, say, when images can’t be loaded in the inbox, as you mention above.

    I wouldn’t use this 48% figure to extrapolate a true open rate. Instead, focus on using open % comparatively to gauge the success of tactics and distinguish which campaigns did best in your email programme.

  • ali rose

    I just did a big email campaign with a beautiful layout that cost me fortune to only find out that most of the people have blocked images and didn’t see my ad!

This blog provides general information and discussion about email marketing and related subjects. The content provided in this blog ("Content”), should not be construed as and is not intended to constitute financial, legal or tax advice. You should seek the advice of professionals prior to acting upon any information contained in the Content. All Content is provided strictly “as is” and we make no warranty or representation of any kind regarding the Content.
Straight to your inbox

Get the best email and digital marketing content delivered.

Join 250,000 in-the-know marketers and get the latest marketing tips, tactics, and news right in your inbox.


See why 200,000 companies worldwide love Campaign Monitor.

From Australia to Zimbabwe, and everywhere in between, companies count on Campaign Monitor for email campaigns that boost the bottom line.

Get started for free