My company emails land in yahoo bulk. How do I get off the blacklist?

This is common anytime you send out an e-mail to multiple recipients. Because of the very fact that you have many recipients, the receiving mail server identifies it - correctly, strictly speaking - as bulk email (bulk=going out to many people at once). You can't do anything about yourself, as far as I know, but the recipients of your newsletter can, by selecting the email from you and then clicking the symbol or link saying "this isn't spam".