Resolving, then. Thanks all!

Cleaned this up (it wasn't namespace aware, check for invalid 
mailboxes, add code to force showing previews even if preview prefs 
aren't on) and committed.

I think path characters work in query strings, but I prefer PATH_INFO 
too. It's really a very advanced feature, so requiring certain server 
capabilities for it should be fine.

Point taken.

Attached is a replacement patch that:

1. uses PATH_INFO, if possible, then tries REQUEST_URI, then just 
defaults to INBOX.
2. uses the /-/new syntax
3. handles vfolders properly

Okay. Another thing that comes to mind is that if a server doesn't 
support PATH_INFO in some cases, it won't recognize rss.php/whatever 
as referring to rss.php - it'll complain that it can't find "whatever" 
in the rss.php/ directory.

Personally I think using PATH_INFO here is much nicer than other 
solutions, esp. since we'd have to escape /'s even if we did 
rss.php?INBOX/foo - unless / after ? aren't path characters?

Thoughts? Opinions? Frogs?

http://koivi.com/apache-iis-php-server-array.php

Not sure where you see that - $_SERVER is from 4.1.0 on, but 
REQUEST_URI comes from the sapi (apache, whatever), and is somewhat 
dependent on it.

According to http://us2.php.net/reserved.variables , REQUEST_URI is 
from PHP 4.1.0

There's a quirk in the GData query syntax, which I was thinking to 
base this on 
(http://code.google.com/apis/gdata/protocol.html#query-requests) that 
should take care of the /new problem. /new is a category, and 
categories should be preceded with /-/ to distinguish them from other 
path elements. So we'd have:

http://server/horde/imp/rss.php - gives all mail in inbox
http://server/horde/imp/rss.php/-/new - gives new mail in inbox

Also, rss.php/INBOX should work as well. I like the REQUEST_URI usage 
to avoid PATH_INFO; any sense how portable it is?

Jan -- yes, I meant to include that potential problem with the 
submission. But...

As per Selsky's question in IRC, the code doesn't handle vfolders 
because I was using MailboxCache directly. The fix is trivial, using 
Mailbox's buildMailboxArray(), but then there is no clean way of 
retrieving only new messages.

Perhaps the /new idea isn't a good one, and that functionality should 
be relegated to a vfolder?

That would mean that people can't subscribe to folders called "new". 
Can't we use a character that is not allowed in IMAP folder names 
instead, or at least one that's supposed to be less common than "new"?

I've implemented RSS feeds for mailboxes in the attached patch. As per 
a discussion with Chuck, the url scheme is:

http://server/horde/imp/rss.php - gives all mail in inbox
http://server/horde/imp/rss.php/new - gives new mail in inbox
http://server/horde/imp/rss.php/A/B - gives all mail in folder A.B
http://server/horde/imp/rss.php/A/B/new - gives new mail in folder A.B

(...where "all mail" is the last 20 messages regardless of status).

The proposed file in /imp/templates/rss/mailbox.rss is identical to 
the file in /whups/templates/rss/ticket.rss, and similarly 
/imp/themes/feed-rss.xsl to /whups/themes/feed-rss.xsl.

Please let me know any changes or enhancements that should be made.

Something like whups/rss.php, but showing content like 
imp/lib/Block/tree_folders.php, so that a summary of all the folders 
and new mail can be fetched through RSS.