We often remind you not to send image-only emails. We have always recommended a combination of text and images in your emails because image-only emails can trigger spam filters.

We have been reluctant, though, to recommend strict text-to-image ratios, even though we’ve heard various recommendations suggesting that the ratio should be 60/40. We hesitated to recommend such ratios because we never saw data confirming or refuting the ratio… until now.

Our friends at Email on Acid have conducted tests that show the 60/40 ratio is unnecessary. But the studies confirm that image-only emails will trigger spam filters. Here are the key points from the tests:

  • Emails with only images will often trigger spam filters.
  • The same email with just 500+ characters of text will not trigger the filters.
  • The 500+ character threshold seems to apply regardless of how many images you have in the mailing.

In other words, the spam filters don’t care about the ratio of text to images. They simply want to see a modest amount of text — 500 characters or more — to let the mailing pass. That’s an easy bar for most email marketers to clear. Just a few lines of text, above or below the image in your email, should do the trick.

Adding text is important — not just because of the spam filters, but also because you want your readers to see something if they have their email reader set to hide images.

Here’s a link to Email on Acid’s article on the subject.


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