A problem plaguing all anti-spam solutions to some extent is that they can block wanted email messages. Legitimate commercial email such as sales reciepts and newsletters are specifically succeptible to being detected as "false positives."
Anticipated Sender is an open standard that hopes to address this issue.
SpamButcher is publishing the Anticipated Sender standard for use by webmasters, legitimate commercial email senders and spam filter developers without charge.
When a user subscribes to an email newsletter or other email service via a website, they will be presented with the option of clicking a link to a specially formatted file containing the address of the message sender.
The file is then automatically processed by the user's spam filter. The spam filtering application then presents the user with the option of adding the sender's address to their list of known email addresses to be exempt from filtering.
SpamButcher 2.1 is the first spam filter to support the standard.
Sample Anticipated Sender Link for email@example.com
(Requires installing SpamButcher or other Anticipated Sender compliant spam filter to use)
Anticipated Sender Implementation Guide for Spam Filter Developers
Anticipated Sender Implementation Guide for Web Developers