How do you personalize messages for your leads, customers and users?

Beyond the obvious name the content of the emails we send depends on what category the user falls into, and a specific timing when to send it. We do segment users based on what they do in our product (toggl.com/hire) and use Intercom and Amplitude for this purpose. Once they meet the criteria (for example signed up in the last 2 weeks, created a skills test, got 5+ test takers) that triggers an email from Intercom with the relevant content.

It depends on the nature of your business. But, personalizing a message begin by understanding or guessing the requirements of the user that you're planning to talk to.