[Wolves] Mail clients

[Aquarius]

OK, OK, you've all pretty much convinced me. I'm looking for
recommendations for a GUI mail client. It must fulfil the following:

- Fast to start up and sleek in usage (no Evolution!)
- Gtk-based (yeah, yeah, I don't care. It has to be Gtk. No arguments.)
- Does IMAP

And the following are nice-to-haves, so as many as possible:
- Virtual folders (folders populated by a search query, not by explicit
  filing of mails)
- Running an external program for signatures
- Changeable keybindings
- Filters that can run an external script to do something with the 
  mail you're looking at
- Filters that can move a message to a different folder
- Filters that can do both, one after the other
- One-keypress add-this-person-to-my-addressbook-with-a-specified-alias
- The ability to bind a key to "save this mail into the folder I have
  allocated for mail from this address". Bonus points if the first time
  I do this on a mail from an address for which I haven't allocated a
  folder, it comes up with a sensible default name and location for that
  folder.
- Alternatively, if virtual folders work, an easy way to say "create
  a new virtual folder showing mail from this address only". Bonus
  points if it's easy to add this address to a previously existing
  virtual folder.
- Scriptable in some way (if the above are doable by me writing scripts,
  rather than by default in the client, that's fine, as long as the
  scripting language isn't Lisp or something)
- Scriptable in Python
- Good drag-and-drop (so I can drag a file from the Filer onto a mail
  and it attaches that file)
- Handles mailing lists well, threading the messages

And possibly:
- is an NNTP client

I'm not sure about the last one, because it violates "sleek in usage"
above, and that's key. I start my mail client about forty times a day,
so it has to be quick. No, I don't want to just leave it running and
therefore not worry about startup times.

All suggestions welcomed. :-)

Aq.

-- 
"Computer games don't affect kids. I mean if Pacman had affected us as
kids, we'd all be running around in a darkened room munching pills and
listening to repetitive music."
	   -- Kristian Wilson, Nintendo