TVD_SPACE_RATIO is not the most common term, however you it plays a significant role while you, the email marketing professional, are trying to optimize an email for spam.

It is the ration between the spaces and non-spaces in your html email newsletter. While spaces are usually not taken into condideration from email clients, same thing doesn’t happen with spam filters.

According to SpamAssasin, spam messages usually contain lots of spaces!

How to fix the TVD_SPACE_RATIO issue

Try to reduce as much as possible the white space in your email.

Having said that, don’t worry TOO much about it, it is just an indication and there’s many more parameters contributing to your email ending up in the junk folder.