I have recently started getting the occasional spam mail after not having this problem for several years. As far as I know spammers typically obtain mail addresses via data breaches or by crawling the web for mail addresses carelessly made public via forum posts etc. I don't think the former applies to me so I was wondering how to "reproduce" the latter, i.e. what methods, tools etc. I could use to find my mail address on the web beyond simply using a search engine such as Google.
There can be multiple sources:
- big random e-mail databases generally available on black market
- specific e-mail databases leaked/stolen from specific sites; those are also sold on the market
- automated tools that phish addresses from web-sites; many site still have addresses in plain text which is a bad practice since it's a trivial matter to extract them
- addresses shared between large companies for (theoretically) marketing or other similar purposes; that's why GDPR appeared
The last one in the list usually guarantees that you end up as spam target. It is sufficient to register on a few big shopping sites with low security and that's it; you'll start getting spam.