Image Blocking: The Basics

As you’re probably aware from receiving email marketing campaigns, images are initially blocked when you receive an email. The aim of this post is to help you understand why the images are blocked, what to do about it, and we’ll even show you an example in action.

First, let’s clear something up – image blocking only applies when sending or receiving HTML emails. Image blocking does not occur in plain text emails, as there are no images included.

What is image blocking?

The majority of email clients, i.e. Outlook, Gmail, Hotmail, Apple Mail etc., currently block the user from seeing images in an email. The user must agree to download the images before they can be viewed.

When are images blocked?

Images are blocked when an email is received in certain email clients. Outlook is one of the popular email clients and blocks images.

Who blocks images?

The majority of email clients block images. However, a recent Gmail update allows images to be displayed once a contact has downloaded the images three times across three different emails, from the same sender. Because the recipient is happy to download the images multiple times, it suggests to Gmail that they are a safe sender.

Only Apple Mail, Lotus Notes and iPad Mail currently displays images as a default. All other clients block images as standard.

Why are images blocked?

Images are initially blocked for one reason: to protect the email recipient from spam.

When a person creates a HTML email that features images, these images are stored elsewhere on the internet. When a recipient wants to view the images, they must give their permission. The images are then downloaded from their online location, and the recipient can see them.

Spammers, people who send spam, are relying on the images being downloaded. Once they have been downloaded, the spammer will know and will continue to send spammy emails.

So before the images can be seen, the recipient must agree.

Whilst we understand this can be frustrating – of course you want the recipient to see the content of your email – the feature is there to help all email recipients. The sending of spam would be a lot more common without this additional security.

How can I change this?

Unfortunately, there are limited ways to resolve this.

Firstly, if a recipient adds you to their ‘Safe Sender List’ (as you can see below), they will be able to see the images, without downloading them every time. Consider including a call to action and ask the recipient to add you to the list.

Secondly, there is a solution – but it doesn’t come cheap. If you’ve ever received an email from a new sender, and the images are already displayed, chances are they’re using Return Path (or a similar system). Return Path offer a certification which authenticates your IP address. This ensures your images are displayed every time, even to new recipients.

If these suggestions can’t, or don’t appeal to you, you’ll have to rely on recipients downloading images. There is no other way around it.


This is an email I received from high end retailer Liberty. I am using Microsoft Outlook 2010.

At first, the images are blocked, and I cannot see the content of the email. I need to download the images to see them.

blocked images




















Or I can add liberty to my ‘Safe Senders List’.

blocked images safe sender






















Once they are added to my list, the images are downloaded and I can see the email.

blocked images turned off






















For a more in depth look at image blocking, click here.

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