Imagine having a personal AI assistant that crafts emails in your unique style, all while keeping your data private and secure on your own device. That's the promise of Panza, a new tool that leverages the power of large language models (LLMs) to revolutionize how we write emails. We all struggle with composing the perfect email, whether it's finding the right tone, recalling specific details, or simply saving time. Panza tackles this challenge head-on by learning your writing style from a small sample of your past emails. It then uses this personalized knowledge to generate new emails based on your instructions, seamlessly weaving in relevant information from your email history when needed. Panza’s secret weapon is a novel technique called "data playback." This process involves summarizing your emails into simple instructions that capture the core message and intended recipient. The model then uses these instructions to fine-tune itself on your writing style, essentially learning to mimic your voice. What’s even more remarkable is that Panza can run entirely on your own hardware, eliminating the need to send your sensitive data to the cloud. Researchers achieved this by using efficient fine-tuning and inference methods, making it possible to run Panza on resources as limited as a free Google Colab instance. While other AI tools might use your data to train models in the cloud, Panza keeps everything local. The researchers behind Panza also tackled the challenge of evaluating the effectiveness of personalized email generation. Traditional metrics like BLEU and ROUGE, commonly used for tasks like translation, don’t fully capture the nuances of style and content accuracy in email writing. They addressed this by using a combination of metrics, including MAUVE, a measure specifically designed to compare machine-generated text to human-written text. This multi-faceted evaluation approach helps ensure that Panza generates emails that not only sound like you but also contain the necessary information. Panza is a groundbreaking step toward making AI-powered writing assistance more accessible and personalized. While this research focused on email generation, the underlying technology has the potential to be applied to other forms of writing, like reports or creative content. However, there are still challenges ahead. Accurately measuring an LLM’s ability to represent personal data is an ongoing area of research. As Panza evolves, addressing these challenges will be crucial to unlock its full potential and usher in a new era of personalized writing tools.