Can you get hacked by replying to an email?

Your machine will immediately start to disintegrate and you will have 5 seconds to evacuate the building before it explodes!

My answer to your question - Can you get hacked by replying to an email is that, if you are sure it is plain text the only things that could happen as a result of you replying are: Someone on the other end knows your email address. You might now be on some spam lists. You may now have leaked information if you are a reconnaissance target.  However, if you look at the email in a web client (like google) and it looks like plain text, don't kid yourself, it could be html, or something else, and it could have something like an embedded image or some other content you didn't realize was there. Clients like Outlook could fool you as well. So be careful. The "text only" email may be more than text only.

My general rule is if I don't know them, or if I don't need to reply (or if I am not curious - in a controlled environment to investigate) why waste my time or risk the issue?!