I wrote an email recently to the author of a book. I'm working on the master's degree in Hungary, the author is a professor in Canada. I'm not a native English speaker. My letter looked like the following:
Dear Dr. [professor's full name],
[body of the email including an introduction with my full name]
With best regards:
[my first name]
When I write to someone for the first time, I make the salutation and the self-introduction formal. But I tend to write my first name as the signature because I feel this shows that I don't insist on keeping the high level of formality I started the email with. In subsequent emails I choose the level of formality to be the same as it happens to be in the reply to my first email.
However, the reply to my quoted email seems to me to be so informal that I don't dare to imitate its level of formality without asking for the international academic community's, i.e. your suggestions. Their letter looked like the following:
Hi [my first name],
[body of the email]
Best, [professor's first name in diminutive (!) form]
So is a signature usually indicative of the intended level of formality? Would it be appropriate to start my reply like this: "Dear [professor's first name]," or "Dear [professor's first name in diminutive form],"? Or can my habit of "imitation" backfire often and make me seem insulting?