u/ALnali-03

I'm a master's student, and I've been working for this professor as a research assistant for almost a year. Today, she replied to my email, signing her first name for the first time. Is this an invitation for me to switch to first name? Before this email, it was always her auto signature with her full name, so I've been sticking to the formal title. I really don't want to offend her or anything. Should I ask her in the email???