E-mails exchange,please advice? -

I got small business as a part of promotion I m thinking to create a sort of Monthly Community news paper that will be supplied online through e-mails as Pdf file and In my database got 5,000 e-mails for people and offices in my city would love to get more at least 50,000 which easiest way can I get more e-mails?if is from companies how can I approach them to exchange e-mails?Please help,would love to hear from you.Thanks

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