The newer name for EarthLink Business customers after acquiring One Communications is smtp-big.earthlinkbusiness.com. That pool of servers require that you be on network using an EarthLink Business data connection.
The servers with the best sending reputation are smtp.earthlinkbusiness.com port 587 (authentication required), or port 465 if you prefer auth+SSL.
How big is your mailing list? ISP shared relays are not the best way to send mailing lists. You'll have a better results using an email newsletter service such as MailChimp or Aweber.