Reason why you're asking this?

because i want to learn from ur expertise

either you have the same e-mail and steam password, which many people still do, or, as of late, they also trigger a login as soon as you gave your steam user name and password and then ask you to provide the auth code as well.

what is 'as of late, they also trigger a login as soon as you gave your steam user name and password and then ask you to provide the auth code as well.'......

im really asking how they get the email address

They did not always ask for the Authentication Code, but relied on those that had the same Steam and e-mail password instead.
The phishing sites used to ask for your e-mail address directly.

Recently though, the phishing sites seem to automatically try to log in as soon as you give away your Steam Account name and password and click "login".
That triggers Steam to send you an e-mail with a new Authentication Code, which the phishing site immediately asks of you in a second step.

They look and feel exactly like the original Steam login page now.

They do not need to know your e-mail address. Once you have the Steam Account name, password and the Authentication Code (all kindly provided by you), they have all they need.
If they wanted to know what your e-mail was (for whatever reason), they can look that up in Steam -> Settings -> Account -> Contact Email once logged in.