Emails to/from sources not gmail are encrypted, but from gmail are not?

Question

My email (hosted via Bluehost) is setup to be accessed through gmail with SSL encryption via the standard setup instructions. However, I've noticed strange behavior. If I am sending emails to webservers I know are also using SSL (such as accounts on my other domains) then I do not receive gmail's "red padlock" indicator of lack of encryption. Also, if I send emails to gmail users there is no red padlock. But, if I receive emails from gmail users, there is a red packlock saying that the message is not encrypted. Various sources report that gmail's messages are indeed encrypted.

What could be causing this issue? Is there something wrong with Bluehost's certificates?

Answer 1

Emails sent to gmail users from your website email which I assume has the same DNS as your site then your emails get encrypted both by your webmail service and gmail (two private keys with two corresponding public keys). If you receive emails from Gmail users then the email is only encrypted by Gmail and not your webmail service and since the message encryption key is accessible to Bluehost, google assumes that the service is not secure.