Email Signatures and Spam Filters

Email Signatures and Spam Filters


Can email signatures make your emails hit the spam filter? In general, it is most often the email content that triggers spam filters, and not the email signature itself. However, there are a few things you can do to optimize your email signatures, especially in terms of images and links.

When you evaluate if you protect your emails from hitting the spam filter, we recommend you first to look at your email server, the recipient spam filter settings, your email subject, your email content/links/images and finally your email signature. Now let’s take a closer look at potential issues with email signatures and spam filters.


The Use of Images in Email Signatures

A common question in our Support is this:

“Is it a good idea to use images in email signatures?” The short answer is YES!

“But won’t images in our email signatures send our emails to the spam filter?” No – but make sure you follow these basic principles to make sure that you do everything right:

  • Keep a proper text-to-image ratio to ensure your emails are delivered. Aim at 80:20 text to image ratio as a thumb-rule to be safe (60:40 text to image ratio can be sufficient).
  • Keep a healthy balance of colors. Most spam filters estimate the intensity of skin and non-skin color pixels in your emails. Especially when you use head-shot photos, it’s critical to test OK for a few pilot users. We’ve also seen emails with campaign banner getting filtered as spam because the banner skin color ration was too high.
  • Don’t add a linked image to your email signature if you have also embedded images. When you add a linked image to your email signature in addition to an embedded image, it can cause the spam filters to raise a flag. Normally they don’t, but if you add several images from several external locations, you’re likely to trigger email signature spam.
  • Don’t link to images with strange names. If you link to an image with a very long or strange system-generated name, it can trigger a spam filter as well. Make sure that the image name is logical and that the url is not too long.
  • Don’t link to images that are located on multiple domains. Some spam filters quarantine your emails if they contain links to multiple sites. You can, without any issue, link to images or landing pages on another url – that isn’t an issue. But don’t trigger a spam filter by linking to 10 different sites in your email signature.

More Advice on Email Signatures and Spam Filters

  • Keep the number of links down. We recommend a maximum of 6 links in your email signature.
  • Check your hyperlinks and avoid using shortened links. Shortened links are often used by spammers to hide the final destination of the link.
  • If you are an Office 365 user, you can secure your domain by adding SPF records (SPF stands for Sender Policy Framework).

Email Signature Software Helps to Avoid Spam Filters

By using an email signature management portal like Xink, you can make sure that your email signatures are formatted correctly so they do not go to the spam filter.

Simply upload your email signature design, or choose a template in Xink, and this way you will make sure that all email signatures across your business are consistent, fully functioning, always updated and work across all devices.

Would you like to arrange a FREE 1:1 demo of the Xink platform? You can also reach us on LiveChat if you have any questions. We are here to help you with all your questions related to email signatures and spam problems – and so much more!




Brand Consistency Through Email Signature