On Tue, Jan 12, 2010 at 11:19:09AM +1300, martin f krafft wrote: > I think [tag leakage] it makes in-headers unusable. After all, I don't > ever want anyone else to know that I tag e-mails from my boss as > "from-idiots", You can cryptographically hash tags so that third-parties can't read the contents of the in-headers. For security, a salt should be appended to the tag name to make dictionary attacks on the tags more difficult. For their owners' convenience, mail clients will want a mapping of hash to tag name. > [...] pseudo-mails stored in Maildir and synchronised by IMAP A single RFC2822 message can store the salt and hash-to-tag database. It could contain a clear subject and directions to the end user not to move or delete it. This would not, I think, terribly confuse existing mail clients or their users. -Dave -- David A. Harding Website: http://dtrt.org/ 1 (609) 997-0765 Email: dave@dtrt.org Jabber/XMPP: dharding@jabber.org