What is this green shield emblem with a checkmark attached to some messages?

When you're checking your email, you may notice that sometimes a green shield emblem with a checkmark will appear next to the email headers. This indicates that mail tracking has been blocked. Many email senders request read receipts when you have seen their message. Another method they commonly use are tracking cookies. These tracking cookies allow the sender to see both when you open the email and what you do online afterwards. This allows them to gather information about your online activities. However, we care about your privacy, security, and peace of mind so we both block these trackers and notify you of their presence.

Read receipt blocking is only available for iOS users at this time, but it is part of our product roadmap for Android and we hope to roll out support for this feature in the future.