September 2nd, 2010
E-mail authentication systems such as DomainKeys and DKIM use a digest or checksum function of a message's header and body to verify that the message to which a signature is attached is the same message that was originally signed. When a mail system forwards an incoming message to an outside address, the message is frequently modified on the way through, even though the SMTP standards encourage mail systems not to do so.
A goal of a good digest function is to survive the changes introduced by typical mail forwarders, while still detecting other message modifications.
The goal of The Forwarding Project is to find out how real mail systems modify forwarded messages, to help evaluate potential digest functions. It sends messages to a variety of different mail systems which then forward them back, with the results collected here.
To add a message to the collection here and run it through the forwarders, mail it as a message/rfc822 attachment to forward@forward.sp.am. The system here will take the message in the attachment and remail it to all of the participating forwarders, and add the original message and the forwarded results to the corpus here. Please put a descriptive subject on the enclosing message since that will be saved as the message's description. If the enclosed message starts with a Return-Path: header, it will be stripped off and that address used as the bounce address when forwarding.
If you run a mail system of a type not represented in our list and you'd like to participate, send a note to webmaster@forward.sp.am with a brief description of your system. You need only provide a single e-mail address that you configure to forward mail back to an address we supply.
Currently the message corpus is only available on this web site. If demand warrants, we can make messages available as downloadable files, or arrange to remail them to registered users' addresses to run them through signature verifiers.