Where can i get a legitimate list of email contacts for a campaign?

I would like to start an email campaign for my website and found theres plenty of legitimate email companies but none of them provide the email list. They're telling me I should harvest emails from people who visit the site. Well DUH if people were visiting my site why would I need an email campaign to generate traffic? Does anyone have any experience with legitimate email advertising where can I get a list of contacts?
Where can i get a legitimate list of email contacts for a campaign?
You can use a tool to get a legitimate.It is very easy to manage.
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