Choosing the wrong forms of address is the fastest way to make a bad impression over email. However, it is one based on norms and therefore is not typically explicitly taught.
In the general case, we can capture how you should choose the form of address via flow chart:
Everyone should have an elevator pitch about their research. When we start out, that pitch is very focused on a particular project, problem, or technique. As time passes, we form a more expansive research vision that can encompass new domains, related problems, and complementary techniques, but still ties everything together in a coherent philosophy, with a long-term goal. My pitch is: programming languages (PL) and software engineering (SE) form the methodological foundation for next-generation advancements in data-driven scientific inquiry. Just as scientific instruments made new experiments and discoveries possible, so too will new programming languages, systems, frameworks, and platforms.