Web Scraping

I found out about scraping today and what it does. I know that it effectively takes information from a certain source, such as twitter, in a non time consuming way in which it would normally take a long time to do or would require multiple people. It seems advertisers are very interested in using methods like these as they are able to scrape thousands of emails to spam to or scrape followers off of social media to see a persons interests. To be able to scrape I know you either need to code it yourself (I only know Java and am not skilled enough to do it yet) or use an already existing programme, but they are all confusing or you need to pay for them.

Anyways, I was wondering if you are able to scrape actual account emails? What I mean by this is the email used to create accounts. I have researched everywhere but no where seems to directly answer the question. Is this possible at all?
*Note: if this not allowed then by all means take it down, I am new here. And for those wondering I am asking out of personal curiosity. I am not asking for you to tell me how to do it if possible, but your guidance and knowledge is appreciated.*

Many thanks.