Final answer:
Whether to use a customer's first name is context-dependent and generally a more formal address is advisable unless the customer indicates otherwise. A professional email address typically includes the individual's first and last name or first initial and last name.
Step-by-step explanation:
Whether it is acceptable to use a customer's first name depends on the context and the level of relationship you have built with the customer. In professional settings, especially when you are in the initial stages of communication, it is generally advisable to use more formal titles such as Mr., Mrs., Ms., or Dr. unless prompted otherwise by the customer. As your relationship with the customer develops, they may indicate a preference for a less formal approach, at which point it would be more acceptable to address them by their first name. It's also worth considering the cultural norms and expectations within different regions or industries. For professional communications, it's important to have an email address that reflects a professional image, ideally including your first and last name, or your first initial and last name.