Would I be in "Blacklist" to send bulk mail by Simplenews? We have thousands of subscribers who sign up through our Simplenews. Now, we would like to send newsletter(eblast) through Simplenews with Simplenews Content Selection too all subscripbers. Will our server getting "blacklisted" by doing this?

PS: The newsletter has unsubscribe URL on footer
As far as I'm aware, your ip gets blacklisted if a couple of people click 'report spam' in the email browser.  Consider setting the SMTP on your server to use a web service such as MailJet who have all kinds of advice on what to do and what not to do.