Spam and Open Relay Blocking System (SORBS) Zombie blacklist


The Spam and Open Relay Blocking System (SORBS) Zombie blacklist is a list of networks that have been hijacked from their rightful owners. In most cases the ownership and WHOIS information of the netblock is changed and then the IPs are sold to other unsuspecting companies.

  • Listings occur as either single IP addresses that host multiple domains or entire ranges of IP addresses from DNS or email hosts.
  • The impact on deliverability is low.

Reasons for getting listed

Servers are listed for:

  • Sending or relaying spam
  • Having been hacked or hijacked
  • Having trojan infestations
  • Using IP space that it does not have the right to use

How to get off this blacklist

This blacklist accepts manual requests to remove IP addresses. First you need to register for an account with SORBS. Then you can look up IP addresses and netblocks in the SORBS database and open support tickets.

You will need to provide proof that IP netblock is legally registered to you through the regional internet registry.

Tips for staying off this list

  • Make sure your servers are properly configured and have no open relays or open proxies
  • Conduct ongoing security checks
  • Verify netblock/IP ownership and WHOIS information
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