The Spam and Open Relay Blocking System (SORBS) Simple Mail Transfer Protocol (SMTP) blacklist lists email servers that allow unauthenticated email to be sent through its system.
- Listings occur at the IP level.
- The impact on deliverability is low.
Reasons for getting listed
IP addresses are blacklisted for:
- Allowing unauthenticated email to be sent from your system
How to get off this blacklist
This blacklist requires securing your email server and ensuring that only authenticated email is permitted to be sent from your system. Follow the retest instructions on the SORBS website.