There may be more SMTP reject error codes that are used by Windows Live Hotmail servers as listed on this page. If you are not an email/network admin please contact your Email/Internet Service Provider for help. We recommend enrolling in our Junk Email Reporting Program (JMRP), a free program intended to help senders remove unwanted recipients from their email list. A block has been placed against your IP address because we have received complaints concerning mail coming from that IP address. Host said: 550 SC-004 Mail rejected by Windows Live Hotmail for policy reasons. If you are not an email/network admin please contact your E-mail/Internet Service Provider for help. Reasons for rejection may be related to content with spam-like characteristics or IP/domain reputation. Host said: 550 SC-001 Mail rejected by Windows Live Hotmail for policy reasons. The typical bounced email messages contains the following error messages: When a Windows Live Hotmail or MSN blocks or blacklists a host, all the mails originated from the IP address will get blocked, and returned or bounced with various error messages. If your emails cannot be delivered or sent to recipients using MSN or Windows Live Hotmail service, chance is the server which is sending the email messages may have been banned or blacklisted due to suspicion of sending spam.