If you receive an email that contains linked images, Outlook does not download those images automatically by default. You can change this behavior if you want, but there risks to doing so. Let’s take a look.
To be clear here, we’re not talking about messages that contain images as attachments or about message into which the sender has inserted images (since those work pretty much like attachments). We’re talking about images that contain URL links to images that are hosted online.
When you get a message that contains images, Outlook prevents the download of those images and shows you a message at the top of the mail.
The reason for this is that Outlook has to download these images from an external server, which means that the server (and therefore the sender) will know that your email address is “live” and being monitored.
This isn’t a problem for legitimate senders like friends, or businesses for which you need a live email address (like PayPal, Amazon, and so on), because it’s fine for them to know your email works. Even here at How-To Geek, we include a tracking pixel in our newsletter so we can remove people who never open or look at our messages because we actively try to make sure we don’t spam people.
But for real spammers, it’s a different story. If they know your email address is active, then you’ll become a bigger target for spam and phishing emails. After all, an account that is known to have a human looking at it is much more valuable for a scammer than an address that might never have a human look at it.
However, even worse than spammers knowing your email address is monitored by a human is the possibility that the images contain a virus or malware. It’s a well-known attack vector, and it relies on people downloading the image to their computer.
So by default, Outlook prevents the automatic download of images—and that’s a good thing.
If you click the message, you get a number of options to deal with this.
The first option, “Download Pictures,” will simply download the pictures for that email, and if you know the sender, then this is probably the option you choose.
To allow images to be downloaded for this user again, or for any messages that come from that domain, you can choose the “Add Sender to Safe Senders List” or “Add the Domain [domain name] to Safe Senders list” options. In the future, Outlook will then automatically download images in emails from users or domains on your Safe Senders list.
If you want to view the image but not through your email client, you have the option of viewing the email in your browser.
Your browser can be a safer place to view a potentially malware-laden image, but are you a security researcher? No? Then don’t open up a suspicious email anywhere, just delete it.
We can’t stress this enough: If you receive a message and you think it might be a phishing email or dangerous spam, delete it and run a virus scan on your computer. Don’t mess around trying to open it “safely.”
Which brings us on to the option in the context menu that we’ve so far ignored: “Change Automatic Download Settings.”
Clicking this option takes you to the Automatic Download settings. You can also get there by heading to clicking File > Options > Trust Center > Trust Center Settings.
Then click Automatic Download to show the settings. We’re interested in the “Don’t download pictures automatically in standard HTML email messages or RSS items” option.
This setting is turned on by default, and comes with an appropriate warning above it.
To be clear, we’re not advocating turning this setting off, as it’s an invaluable protection against both spam and malware. However, if you’ve turned your Junk Mail settings up all the way to Safe Lists Only (where mail from any sender not on your Safe Senders list is considered to be junk) then you could turn this setting off as long as you don’t move items from unknown senders from your Junk Email folder to your Inbox.
However, there are a number of default settings turned on which allow images to be automatically downloaded from safe senders, trusted websites and RSS feeds, so there really is no need to turn it off unless your circumstances are quite unusual.
So again, we don’t recommend turning this setting off except in very specific circumstances, but that’s how to do it if you want to.