Spam reporting service.

Provides advanced technologies and solutions to enhance the capabilities and manageability of e-mail.

System of clients and servers that collect and count checksums of email messages in order to detect and filter bulk UCE.

A mail filter, written in Perl, to identify spam using a wide range of heuristic tests on mail headers and body text. Free software. Can be used as a standalone mail filter, or from procmail.

Free to individuals. Fights spam by putting a copyrighted haiku in the header that is only licenced (for a fee) to bulk mailers who respect codes of practice. This enables the identification of spam.

Open source automatic mail classification tool using Bayesian statistical methods. Offers details about installation and configuration procedures for the windows client.

A free e-mail forwarding and spam filtration service.

Enterprise level email protection and message management services.

Server-based challenge/response system that works with all POP3 accounts.

Consumer opt out registration form for the Direct Marketing Association.

"Spam Agent" software offers content based filters for spam filtering in both home and corporate environments.

Content based spam filtering software.

Provides disposable e-mail addresses. Users can also set up rule sets for trusted or permitted senders.

POP3 service that blocks spam using sender verification methods.

Only allows mail from people you know. Spammers have to pay the users to send them spam.