Gmail showing authentication info

Yesterday Gmail announced on their blog they would be pushing out some new UI to users to show the authentication and encryption status of email. They are trying to make email safer.
There are a number of blog posts on WttW for background and more information.

The short version is that TLS is encryption of the email between the sending server and the receiving server.  It means mail can’t be intercepted or changed while between one server and another.
Gmail is now showing users whether a mail was sent using TLS.
If a message is sent without using TLS, there is an open red lock shown.
Open red lock = unencrypted
If you hover over the open red lock, Gmail tells you the “message was not encrypted”
Hover showing "message not encrypted"
Using TLS removes the open red lock.
Mail sent over TLS
These messages went to spam because, well, do you know how hard it is to find a mail server that’s not authenticated? I ended up sending using SWAKS from one of our VMs so I could control a whole bunch of things, including whether or not mail used TLS. Interestingly enough, Gmail was happy to accept the mail over IPv6 but temp failed anything I sent over IPv4.
Gmail is, apparently, also notifying if mail being sent is going to a recipient on a server not using TLS. I don’t have an easy way to test that.


  1. Anthony Chiulli says

    Hi Laura – for your last comment about not having an easy way to test whether mail being sent is going to a recipient on a server not using TLS, I have found by hitting “reply to” some of my inbound promo emails in Gmail, it will also show a red broken padlock, indicating the mail’s destination email service is not using TLS. I have a couple examples of both if you need them.

    1. laura says

      Yeah, that doesn’t seem to have been rolled out to my account, yet. I tried doing that and got nothing – although it’s possible most of the mail into my google address supports TLS.

  2. Karl says

    A friend has a email address. Gmail marks all of her email with the red broken-padlock. Is this common for email?

    1. laura says

      I don’t know for sure, but it’s unlikely to be anything your friend can fix.


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