Secure your server

When your mail server gets listed in HRBL, its users will be unable to send messages to those destinations where the HRBL blacklists are in use.

Although you can delist your mail server, it is better to secure it first to prevent sending out more malware and being listed again.

Secure first, then delist.

If you are an administrator of a blacklisted server, then do the necessary steps to make your server secure. Just a quick list:

• Ensure it is not an open relay.
• Ensure it is not compromised.
• Force your users to use strong passwords.
• Use authentication in receiving mail from your users.
• Filter outgoing mail through a spam and virus filter to catch outgoing spam and viruses.
• Use SSL when authenticating your users on IMAP, POP3, SMTP, FTP, webmail, etc.
• Keep softwares you use on your servers updated, take security upgrades with special care.

If you need help you are better to hire a professional.

If you are a user of the blacklisted server, then call your email service provider (sometimes it is the same as your internet service provider) and show them the error message you got back. If they want to solve the problem, that will be enough for them.