There are three main reasons recipients may not see images in your emails: their email client is blocking externally hosted images, their email client doesn't support background images, or a firewall is blocking access to our image servers.
To cover all situations where images may not load, we recommend always including a link to the web version of your email, setting the alt attribute for all images, and using a mixture of text and images in your email rather than basing it solely on images.
Blocked images
To keep email sizes down and increase deliverability, images in emails are hosted on our servers, instead of being sent with the email. Email clients refer to these as "remote" or "external" images, and may be set to display images in:
- no emails
- a specific email (as an exception if images are set not to display)
- all emails from a specific or trusted sender, or
- all emails
All desktop and webmail clients have settings like this, which might be applied based on personal preference, or controlled by a system administrator. In any case, it's not possible for you to override these settings, so your best strategy for dealing with image blocking is:
- Keep your subscriber list well maintained and engaged with premium content they want to view.
- Don't use emails based solely on images, include text as well.
- Make sure all images have the alt attribute set.
- Provide a web version link in the email.
Image display options for popular email clients are as follows:
| Email client | Shows images by default | Can set to always show images | Can temporarily show images for a chosen email | Can set to always show images from a trusted sender |
| Apple Mail (mobile) | ||||
| Gmail (mobile and desktop) | ||||
| Outlook 2007 — 2016 | ||||
| Outlook.com/Outlook Mail | ||||
| Yahoo Mail |
If a recipient does not display images, it will affect how we measure open rates.
Background images aren't supported
A number of email clients, including multiple Microsoft Outlook versions on Windows, do not support background images. We recommend picking a background colour similar to your image as a fallback.
See the email client usage report to see how many of your subscribers use Outlook.
Strict firewalls
Strict firewall rules, such as those found in government organizations, may block our image hosting domains. In this case, the recipient's firewall administrator will need to change the firewall rules for them to be able to see images.
For recipients having issues with their firewall blocking images, the image domains that firewall administrators can allowlist are:
- cmail.com
- cmail1.com through cmail20.com