How to address professors in emails? I have been greeting all my professors as "Professor (last name)" in emails I send to them. I think this is normal, but at my university all the professors/lecturers use their first name when ending emails they send.

For example, if the teacher's name was "Joe Smith", they might end an email they send as follows:

Regards,
Joe

This behavior is the case with all of the professors I've had, so it seems to be something that's global to the university. Should I be addressing my professors by their first name in emails? I would have done so already, but I don't want to sound disrespectful. I've looked it up but haven't found any guidelines my university gives on addressing faculty.

Also, I think this question is different from others because as far as I know, my university is an exception with all professors using their first name.
If in doubt, "Prof. Lastname" is always appropriate for an undergraduate addressing a professor.

I sign all of my emails with my first name, but would find it quite strange if an undergraduate student started addressing me by it, unless we had done research projects or extensive service together justifying that far more intimate form of address.