Google made the internet safer when they started to use HTTPs as an SEO ranking signal. This encouraged millions of website owners to serve their website content over HTTPs (using an SSL certificate). They are doing it again but now with email.
In both Gmail and Google Apps, there are now two indicators of security.
Security indicators when sending email
When sending an email message in Gmail or Google Apps, you’ll now notice a red open padlock image if any of the recipients don’t use an email provider that provides secure TLS connection (TLS is an updated version of SSL). If you see the padlock this effectively means that your email message won’t be encrypted during transmission.
Security indicators when receiving email
In addition to being aware if the people receiving our email messages use TLS, Google also advise us of security when we receive messages in Gmail or Google Apps. Per Google “users who receive messages that aren’t properly authenticated with either Sender Policy Framework (SPF) or DKIM will see a question mark in place of their profile photo, corporate logo or avatar”. You may read more about SPF and DKIM on this blog.
This is an awesome initiative from Google as we can now be more sure that the messages that we receive are from whom the person is specified as being the sender.
Mailchimp and Email Security
If you use Mailchimp you have no need to be concerned. Mailchimp authenticates and sends for you in a secure manner.
Mandrill too will send with opportunistic TLS (i.e. send messages with TLS whenever possible). Mandrill requires you to add SPF and DKIM records to your domain before Mandrill will send on your behalf.