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For the most current results on image blocking in email clients, view our updated post.

Many people, either by email client defaults or personal preference, are blocking images in the HTML-formatted messages they are accepting. And then there are a small number of people who block HTML entirely. As David Greiner points out, according to a study by Epsilon Interactive 30% of your recipients don’t even know that images are disabled. In any case, it’s logical for recipients to block images and good practice for us to prepare for this scenario.

So what happens to our emails when images are blocked? What are the best practices for ensuring accessibility and optimizing presentation therein? What are default settings across the board? Let’s get down to answering these questions.

Default Settings in Popular Email Clients

Every client has its own default settings regarding displaying/hiding images. And while most email clients have a setting to turn images on or off, some offer conditional settings which are contingent upon known senders or other factors. The following table outlines the default settings of popular desktop- and webmail clients. (Note that I’m reporting the settings of my personal versions of each client and that settings may differ from one version to another.). I have included contextually-relevant references to ALT text as part of this article. For a more in-depth look at how ALT text renders in popular email clients, you may want to read a more comprehensive article I wrote about ALT text.

Image Blocking in Webmail Clients
Client Default Img Display Trusted-Sender Img Display Renders ALT Text
Yahoo Mail on No No
Yahoo Mail Beta on Yes Yes
Windows Live Mail off Yes No
Gmail off Yes sometimes
.Mac on No sometimes
Hotmail on Yes No
AOL on Yes Yes


Image Blocking in Desktop Clients
Client Default Img Display Trusted-Sender Img Display Renders ALT Text
Apple Mail on No No
Thunderbird on Yes Yes
Outlook 2007 off Yes sort of
Outlook 2003 off Yes Yes
Outlook Express on No Yes
Lotus Notes on Yes Yes
Eudora on No sort of
Entourage on No Yes
AOL off Yes No

So now that we’ve covered the settings in popular email clients, let’s outline how we can help our emails survive image blocking.

Recommendations for Successful Deployment

From my perspective, an email is successful when it meets the following goals:

  • Retains visual integrity in the most commonly used email clients with images enabled.
  • Retains readability in the most commonly used email clients with images disabled.
  • Is readable to people with visual disabilities and navigable to people with mobility disabilities.
  • Is low in weight for recipients using mobile devices and dial-up connections.
  • Is deployed to a permission-based list of subscribers.
  • Meets CAN-SPAM Act requirements.
  • Legitimately passes common tests employed by spam filters.

Looking at this list it becomes clear just how important it is to consider image blocking when designing/developing an email. Dependency on images can lead to failures on many different levels. Preparing for a scenario in which images are disabled puts us at an advantage to oblige the settings/preferences of a broader range of recipients.

Become a “Known Sender”

Nearly every email client in my test suite enables people to automatically display images when a message is from a “known sender” (senders appearing in white lists, contact lists or address books). Because our subscribers have requested to receive emails from us, they will naturally want to ensure they receive the messages. Spam filters can disrupt legitimate communication when subscribers are unaware of how they function. With a couple, simple notifications we can increase our chances of success:

  1. Ask a subscriber to add the email-list address to their address book (right on the subscribe form) and briefly explain why.
  2. Enable a double opt-in subscription process, and send a plain-text confirmation which includes a request to add the email-list address to a recipient’s address book. And, again, briefly explain why.

Informing a subscriber about this simple step will increase our chances of images being enabled and will help us legitimately pass through spam filters.

Prepare for Disabled Images

So we’ve created a structurally-sound template, we’re preparing to send our email to a permission-based list of subscribers and we’ve taken steps to see our list email-address into the address books of the said subscribers. There are still a number of people on our lists who will intentionally block images, and therefore we should account for that scenario.

I wrote an article outlining a technique for this very purpose. With the releases of Yahoo Mail Beta and Windows Live Mail we lose the ability to integrate the aforementioned technique. However, Ryan Kennedy from the Yahoo Mail team has pointed out that they are looking into potential resolutions for this obstacle.

Positioning aside, there are some things we can do to retain the integrity of our emails when images are disabled:

  1. Begin an email with HTML text or logical ALT text. We can decide what a reader sees in a preview pane or small message-window. If we’re prepared, we can optimize the experience of scanning messages. Moreover, some applications offer the ability to preview the first few lines of text before an email is loaded/viewed.
  2. Use ALT text. This seems so obvious I’m almost embarrassed mentioning it. However, I don’t have enough fingers and toes to count the email newsletters I receive sans ALT text, so there it is.
  3. Use captions for contextually-important images. In lieu of proper support for ALT text across the board, we can add captions to images which are vitally important to the content of an email.

Avoid Image-Based Emails

Again, this is something which should seem obvious. But image-based emails are often practiced as a simple, easy method of delivering a pretty design irrespective of the rendering circus among the array of common email-clients. When we ponder image blocking as part of the rendering equation, it’s easy to see how an image-based email could be completely destroyed with a single preference. Furthermore, this doesn’t take into consideration file sizes for mobile/dial-up recipients, accessibility for those visually impaired or the HTML-to-text ratio that popular spam filters apply with their algorithms.

In summary, we should be giving serious consideration to image-blocking and what we can do about it. It’s natural and reasonable why people disable them, but with the right approach we can improve the experience for our subscribers.

  • jim

    How about plain text, multi-part and even valid html? I’d consider these things as best practice for “ensuring accessibility and optimizing presentation therein?”…

  • jim

    agreed, but best practice to handle people who block images (or html) in my mind is a plain text email…

    …saves bandwidth too ;-)

  • Leon Breedt

    Several mail clients (such as Outlook, GMail, etc) render images without any blocking if the HTML part of the email (say a multipart/related entity), has image attachments with a Content-Location on the image attachment matching up with the ‘src’ value of the tag in the HTML.

    I’m not sure why this is the case.

    However, this is prone to abuse, wastes bandwidth and is even more likely to (1) get your message blocked as spam (2) infuriate recipients.

    If you’re set on delivering it as such, would recommend at least wrapping the multipart/related part containing the HTML & images with a multipart/alternative part having a plaintext version.

  • wayne

    Leon, I believe the reason that mail clients block images is for privacy reasons, not bandwidth-saving reasons. See Web bug.

    If the image is attached to the email, then there is no privacy issue, and thus the email client can “safely” display the image.

  • Beth

    I am blind. Just thought you might want to know that in re: accessibility most JAWS users turn preview panes off on Outlook — they’re just another distraction to JAWS. The article says that lots of people have graphics turned off in e-mail also–which means they’ll just get little outline frames where banners, photos, and other graphics appear.

    Maybe some of the same tricks you use for accessibility, the ones that turn out being good for blackberries and cell phones, might be useful here. You know, use graphics judiciously (and don’t count on them carrying the important messages) and use strong, short, information-rich text?

    That way even if graphics are turned off and only a small pane is visible, we’ll get the gist.

  • Dave Greiner

    Great suggestions Beth, thanks for chiming in.

  • jo

    So why don’t more newsletters use html with images attached?

  • Laurie

    Jo, speaking for myself, if I get a newsletter with image attached – I am not going to open the attachments even from trusted sources. With the various virus trickiness in the past (Anna Kornikova pics anyone?) – it’s just plain bad practice and manners, and people are not going to risk opening a potential virus. I suspect there are a LOT of people like me who won’t open an attachment.

    So it’s not practical from a newsletter production point of view.

  • Jamie

    If you use a multi-part mime message and base 64 encode your images and then use the cid eg. then Outlook, Outlook Express, Thunderbird, Yahoo, Hotmail all display the images by default and both Outlook and Outlook Express don’t show any attachments present so there are no attachments that need to be ‘opened’.

  • Dave Greiner

    Jamie, while that’s true for the providers you mentioned, there are many other web-based email providers that do not support image embedding. Because of this, we go for the industry standard which is externally referenced images.

  • Béate Vervaecke


    This is a great overview. I have two questions:
    <ol><li>I thought Outlook Express (at least in Europe) comes with default image blocking, is that correct?</li>
    <li>Could it be that Yahoo Beta very recently changed it policy and has the images now default on off?</li>

    Best regards,
    Béate Vervaecke | e-Zen

    Best regards,</ol>

  • Gabriel

    I use Outlook Express 6 with default settings and while it blocks url based images, an embed image will still show without trouble using the technique mentionned by Jamie.

    However, i’ll also add the new Windows Live Hotmail to the list of email providers not showing embed images. The “old” Hotmail interface stilll do show them.

    Also, i came across “Goodmail Systems” who apparently offer a possibility to bypass spam filters. I don’t know if it affects on embed images being shown but i’ll just mention it if it can be of interest to someone.


  • kms

    Mac Mail 3.0 comes with built in stationary. Does anyone have an idea about how those templates are being received?

  • jgl

    What about postcard style design like REI, Crate & Barrel. They look nice but does this suffer on functionality/usability. There are a lot of big name companies using this type of style….. What do you think?

  • Dave Greiner

    Jgl, I think they need to adapt to the changes in the email landscape or their ROI is going to continue to decline.

  • Ben Dash

    It looks like Yahoo doesn’t work with multipart/alternative, but gmail does, just FYI.

    Try pasting an image into an html email on outlook and then send it to a gmail account and a yahoo account and you’ll see what I mean. Yahoo displays both the text/plain and the text/html, but doesn’t embed the image.

  • Dave Greiner

    Cheers Ben, we looked at this ourselves and it turns out embedded images are blocked by default in most of the major web-based email clients, including Hotmail, Yahoo! Mail and Gmail. Just like externally referenced images, they display by default if you’re considered a safe sender by that recipient.

  • Coder

    I am looking for a solution to the images blocker in outlook 2007?

    Can you help?

  • Oliver Smith

    I got my email to work in all clients except Outlook 2007 which is a real pain as more and more people are using the office 2007 stuff when they should be using thunderbird.

  • Dave Greiner

    Coder, sorry, but unless you can get your recipients to add you to their address book or safe sender lists, images will always be turned off by default.

    Oliver, we collectively feel your pain there. We managed to get some pretty good results with our free templates, so that might be a good starting point for your next template.

  • Asian

    I am looking for a solution to the images blocker in outlook 2007?

    Please help.

  • huzefa husain

    how to remove the attachements from the newsletter email
    when i m sending a newsletter to anyone, the images which i have used in the design are being attached with the email

  • Sohbet

    I am looking for a solution to the images blocker in outlook 2007

  • zurna

    thanks :)

  • chat

    Every client has its own default settings regarding displaying/hiding images ????

  • David A

    Is there a way to position an vcard in the body of an HTML email.
    I use the addbusinesscard method in VBS but it always puts it at the top of the message :(

  • Phil Oye

    I’m a bit late to the party, but I’m wondering how CSS image replacement fits into all this.

    What is the state of the art for including an image masthead/logo in an email?

    I notice that Campaign Monitor’s own mass emails apply a background image to the table cell of the masthead to produce a gradient and then place the logo as an regular old image inside the TD. The Alt tax simply reads “Campaign Monitor” and doesn’t appear to be styled in any way.

    There was an article on this site from more than a year ago, CSS Solution for Image Blocking. It would seem to be right solution for what I need (style the replaced text when the image is dropped), but omit the text if images are shown.

    However, as it is almost 1.5 years old, I wonder if it is still valid. Outlook 2007 isn’t on the list for example.

  • Dave Greiner

    If anyone is interested in my reply to Phil, check out this forum post.

  • kevin dodd

    Does anyome know any free email clients that allow you to embed images in the email rather than attaching them?


  • Gburya

    I am trying to figure out how to send an image that is NOT considered an attachment. For example. I have an email with 4 small images in it. When I send it to someone with outlook 2003 it displays the images in the proper place within the email. But when I send it to myself (using my hosting of my website mail system) where I use Yahoo, it makes ALL images an attachment, and thus when displaying them shows them out of place, and all at the bottom of the email. It just shows place holders for where they are suppoed to be at. No matter what I do, accept them or not etc.. how can I fix this? Even if they are blocked, until someone hits the display images button, that is ok, I just want them to display in the correct place within the email once they choose to display the images. HELP!! Lol!!

  • a.m.organicity

    1) all the email vendors have added image blocking to their products
    2) people seem to actually like this new image blocking thing

    Do e-mail marketers want to get images back into their emails, or do they want to respect their recipients’ new preference?

    Although this image blocking is pretty new to most people, once they learn to accept it and like it, what will be the backlash of marketers returning images to their inbox in the (near) future?

  • Todd

    This is a great post! And now i’m going to stump you all. Alt text is not working in yahoo mail and aol 9 with images off. I use a couple test accounts to preview clients email. I also use some mail inbox inspectors. And in both ways, the images are not just turned off (which then shows the alt tag) they are blocked. The end result is a page full of grey boxes and no alt tags.

    Has anyone else seen this to confirm my worst fears about alt text?

  • Free CSS Templates

    I got my email to work in all clients except Outlook 2007 which is a real pain as more and more people are using the office 2007 stuff when they should be using Thunderbird.

  • RallyFan

    Tabular layout of the email with absolute image sizes (width = height=) defined in the src declaration will ensure that at least the layout of the email is kept consistent. Then styling the background color of each image’s table field will further ensure at least the email is delivered in the desired form – if I get an email coming in (which has it’s images blocked initially) and it’s all over the place I’m less inclined to click the ‘allow images’ button, whereas, if it’s a correctly structured (hence readable!) layout I may give it the benefit of the doubt…

  • EoN

    Ok. Firstly, in EVERY discussion about images & their rendering in different clients, a critical piece of information seems to be missing in a lot of peoples comments – whether they’re talking about ‘attached’ (embedded) images or ‘remote’ images. Email clients treat this differently.

    Remove images – forget ’em, they’ll always be hidden/blocked by default.

    From what I’ve seen, MOST of the new email clients ALSO hide/block Attached/Embedded images by default. Including Outlook 2007, Windows Live, Gmail & Yahoo.

    Or to paraphrase, almost ALL clients block ALL images by default now.

  • SEO

    Hi Guys,

    I’m having a major argument with regards to the following:
    Which is better:
    1. Integrating images in outlook (bypassing image blockers)
    2. Pulling them from HTML.

    If 1. is the solution please can someone send me a link on how to do this.

  • Dave Greiner

    Most email clients block embedded images, just like those referenced externally, so that won’t really make much of a difference, especially to web-based email clients.

  • Melina

    Anyone knows what is actually causing slow image loading? Different email clients seem to download the images at a different speed causing problems. Also, what do you think is the optimium speed for image loading.

  • Lydia

    Hotmail – images blocked in the body of the email. To see imbedded images in the email instead of opening up each image individually as an attachment, just check off the Rememer Me/Save my email address on the PC. That worked for me.

  • Paul

    I use Thunderbird 1.5 and my good buddy uses Outlook 2007. Whenever he sends me an email with an embedded image, it does not show. I am not blocking remote images.

    Is this an issue with Thunderbird and my settings or his?


  • Rules

    agreed, but best practice to handle people who block images (or html) in my mind is a plain text email…

    …saves bandwidth too ;-)

  • Jo

    I have a similar problem as Paul. Whenever I get mail with with an embedded image, it does not show although they used to. Not change any settings and I am not blocking remote images using Outlook 2007.

    Any help?

  • Iwona Matlingiewicz

    I think that blocking images & html code in email is correct! Look what’s happening around – how many people want to gain acces to our computers. And I advive against outlook 2007 – it’s full of bugs and not nice interface. regards -)

  • wsdcent

    How about groupmail? is it posible to block images too
    Download groupmail here http://www.wsdcent.com/des/download-tag-3-IDS-215.htm

  • JeremyDempsey

    Many ESP’s also offer message rendering tools integrated right into their applications so you can see how a messsage is going to render on mobile devices, web based and installed email clients with images on and off prior to deployment. Saves alot of time and money on guessing of how to design for “the average rendering” across multiple devices and platforms. Here’s an example: http://eloop4.goldlasso.com/UserFiles/c_315/Image/enhancedmessagetesting-gl.pdf

  • Dave Greiner

    Thanks Jeremy, but that advanced testing functionality is already available in Campaign Monitor.

  • GotMail

    I don’t necessarily recommend not sending HTML with images – most e-tailers are doing a great job with alt tags and such. We send over 20 million pieces of email/month and have yet to see a huge drop in opens, clicks or ROI. Bottom line – if you’re a trusted sender and you test (ie. Pivitol Veracity) in multiple clients, you’ll be OK.

  • OFE

    Many of mails im getting with Outlook 2007 are blocket. That kind of email doesnt look good and me as potencial customer, not interested in receiving such emails. So other point I prefer sending plain text email to my potencial customers. Nothink to block then ;)

  • Keri Russel

    Then styling the background color of each image’s table field will further ensure at least the email is delivered in the desired form …

  • Pfezziwg

    I cannot send html email with images to Hotmail but I can to Gmail.

    I can receive other newletters in my hotmail account with images though.

    Is it because they have a ‘trusted sender’ approval from Hotmail. Is it only professional newsletter email service providors that can work with Hotmail now?

    Staff, healthcarerreviews.com

  • szyby samochodowe

    I use outlook express and I like that client.
    Blocking images in email to let faster downloadnig everything information.
    I have the problem with coding UTF-8

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