Spam is crippling email. So far no mechanism has been shown to have a long-term, large-scale effect on reducing global spam. Some spam control techniques rely on an assessment of the sender's reputation. When a mail sender adheres to a set of best practices, and is accountable for their use, it is possible to treat email originating from them with less suspicion. This translates into significant antispam resource savings for the mail receiver.
VBR (Vouch By Reference)
Alt-N Technologies, through its participation in the Domain Assurance Council (DAC) is working to create an extension to Internet mail called "Vouch By Reference" (or "VBR" for short). VBR provides a mechanism through which certification providers may vouch for the email messages sent by others. VBR is based on the idea of adding an additional header to the outgoing mail and providing a very simple way to check whether certification providers vouch for a particular sender. VBR does not require the certification provider to sign (or even know about) any mail that is sent.
MDaemon includes the world's first commercial implementation of VBR and handles all the details for you. All you have to do is configure your MDaemon with one or more certification providers you trust to vouch for incoming mail, and one or more certification providers which are willing to vouch for your outgoing mail. Ultimately, it is our goal to have all the major reputation service providers create certification servers for your use. They will certify only those who meet their criteria for "good email practices". Until that day arrives, Alt-N Technologies will step into the role and provide certification services for the MDaemon community.