Yes. AS you said; never reply or click a link, no matter how tempting it may be. The mail that goes to your junkmail folder depends on your filter settings and your ISP's filter.
Most often it is rubbish advertising, spam and scams tagged by you ISP or webmail service. If you subscribe to forums and have your settings set to receive all contributions, it will often end up in your junk folder because of the repetitive nature of the mail sender. You can usually set your mail client to accept mail from certain senders, whatever it is.