Spammer registered users

In my website, I have a lot of spammer users registered before installing Antispam module. Is it possible to determine which users are
spammer and which are not, from IP address and email addresses? Antispam module can help me for that purpose?

Also is it possible to prevent spammers to register to website? After installing Antispam and enabled Akismet module, spammers continued to register to website.

PS: I installed and enabled recaptcha module. But this does not stop spammers to register to website.

Is antispam module interested in adding spam content and not interested in registering spammer accounts?

thanks