Image blocking is now a common anti-spam feature for email clients. The concept behind it is to stop spammers placing a web beacon (an invisible 1x1 pixel image) within the message to determine if the address they have sent to is valid. This also happens to be the same technique used by permission marketers to track opens.

The blocking of images therefore causes the following issues:

1) Inability to track opens
2) Email creative is mangled

Here are some suggestions for tweaking your creative to prevent any major image blocking disasters:

1) Define image sizes

Within your HTML code make sure you state the height and width of the image. Failing to do so could lead to any blocked images being stretched across the whole of the message and pushing other elements of the email out of sync.

2) Place ALT tags against all images

Some email clients will display the alternative text when blocking the image. If you insert this text it will enable your recipients to get a better understanding of what should be being displayed.

3) Is your text hidden?

Background images that are used behind a block of text can make the text disappear or become difficult to read when images are blocked. Try and avoid these and simply use a background colour instead.

4) Offer an online version

Place a link at the top of the email to a hosted version of the message. This will allow recipients to view the message as intended with all of the images displayed.

However when images are blocked some email clients such as Hotmail will also stop users clicking on this link.

5) Encourage the addition to the address book

If your recipient has you’re ‘From’ address in their address book then the chances are your email will be displayed with all of the images. It certainly will not harm to have a line of text at the top of the list asking them to add it.

It is also important that you stick to a single ‘From’ address for your newsletter. If you change the address then the user will have to add another address.

While some actions can be done to prevent image blocking such as checking the email message against junk mail filters, standardising on a ‘From’ address and encouraging users to add you to their address book you will never get away from the fact that some of your messages will have their images blocked. Therefore you need to take action to make the best of the situation when images are blocked.

One option to help you overcome these issues and to craft your creative for when images are blocked would be to use a service such as Emailcenter’s Deliverability Service that provides screen shots of your email in different email clients.

By carefully checking each message and monitoring your open rates you should see the impact of image blocking kept to a minimum.