On Tue, 15 Dec 2009 19:54:11 -0500, Alec Berryman <alec@thened.net> wrote:

> There are security concerns (need to strip incoming messages of tags so
> no one tags your mail for you), privacy concerns (if you forward the
> entire message as an attachment, may want to strip tags), and space
> concerns (how many flags?), but I think they can be worked around.

I agree that the labels-in-headers approach has some nice advantages.  I
haven't thought through merging of tag lists, but maybe that is no worse
than other approaches.  One thing that worries me a bit is that notmuch
updates tags often, and each of these updates would require rewriting
the message, at least in the obvious implementation. I'd hate to finally
have Xapian issue 350 fixed, only to take an equivalent hit by rewriting
the message. Maybe it is not that slow.

d