The Missed Spam Blocklists (MSBL) project is an incubator for anti-abuse, anti-spam and pro-privacy technologies in the field of non-broadcast (private) electronic communications, such as email, SMS, instant messaging, and VOIP. It promotes development of new methods of stopping spam and other forms of network and messaging abuse that established anti-abuse and anti-spam tools miss. Its mandate also covers technologies that enhance user privacy and security within non-broadcast electronic communications platforms.

The MSBL is currently focused on developing HASHBL blocklists, blocklists that store data elements as cryptographic hashes. The first MSBL project, the Email Blocklist (EBL), is a HASHBL that lists email addresses as SHA1 hashes. It is currently in first stage, private beta testing.