Hi {{first_name}},
We just shipped [[new feature or product update]], and it's specifically relevant to what your team was using [[your product]] for: [[their previous use case]].
Here's what it does: [[1-2 sentence description with the outcome it enables]].
If you're still solving [[the problem they were originally trying to solve]], this might be worth a fresh look. Happy to do a quick walkthrough.
[[Your name]], [[your company]]