Sometimes there are cases in a e-mail correspondence with academia staff (professors and bureaucrats) in which I don't know which is the best practice. I wonder if there is any best practice for the following cases:
Reply to a reply: when I ask for information via e-mail, and the reply gives me all the information I want, should I send an email just to thank them, or is this considered a bad, time-consuming practice?
How does a professor react to this kind of reply? And what about a bureaucrat (who maybe receives more e-mail)?
If I asked for an internship and he gave me a negative response, is not replying to him considered rude or normal?