Google is pushing to have email encrypted and are doing it by providing this warning to get other users to also push for encryption. However, less than 25% of email servers are capable of encryption. This is because there is no standard for encrypting email. As a result, those servers that are capable of encryption are not all doing it in the same way. As a result, if everyone were to suddenly require encryption, very little email would actually get through because not everyone is capable of it and there would be major issues with compatibility with those that are.

The encryption that Google is referring to in the warning (SSL/TLS) does not actually encrypt the email. It does encrypt the transmissions between the two servers that are communicating, but it does not encrypt the email itself.

Google is not improving inbox deliverability for those that choose to use encryption. Currently, a vast majority of email on the Internet is not encrypted and it will likely remain that way until formal standards are adopted. Once they are adopted, universal encryption will probably happen very fast. In summary, there is no cause for concern and this warning is to be expected, especially for emails that are sent from email marketing platforms such as Luminate Online.