I'm no expert. I'm not even a beginner, as I have read some about it, but haven't begun yet. But, I will try to answer your question based on what I have read. Email marketing appears to still be very useful, but you have to provide valuable content to a target niche, otherwise the subscriber will unsubscribe you, as they have a ton of other stuff to read. The days of getting results for spamming are over. There are actually laws about spam in the US. Good luck!