Outlook:mac 2016 was released this year. The UI was even more Windows’ish than before. Email signature capabilities were exactly the same as the previous version but the overall user experience was improved with every release. This release was particularly good!
The best email clients (apps) in 2016 were probably Outlook (as OWA faded away), Inbox by Gmail and Gmail. These apps were becoming the standards from 2016 for business users. Other complete secure email solutions also began to get popular such as Email+ but that was more a complete solution rather than just an app.
Take a look at this comparison of email apps with “email signature eyes” from 2015: https://wpxinkio.wpengine.com/email-signature-ipad-iphone/email-apps-review/
Bonus info: The Segway personal robot gets a robotic face 🙂
Take a look at the other email history posts from the Xink Advent Calendar!