How to set up Emacs as a mail client (with mail saved/filed on an IMAP server)

[nljlistbox2]

I've been reading about getting email set up in Emacs for the past several 
months, but I haven't yet come upon a satisfactory solution for me. I have a 
few questions that I hope someone might answer.

1. Gnus: It has often been observed that mail and news are similar creatures, 
so that it makes sense to handle mail in a system built for handling news. 
Certainly there are similarities. However, when I've read a news article in 
Gnus, it disappears. That suits me well enough. But I don't want the mail in my 
inbox to disappear once it's been read. I'd like to be able to see both my read 
and unread mail in my inbox and have the two distinguished in some way. Doable? 
I'm guessing it is, but the second issue has precluded me looking up how to do 
it.

2. Gnus again: As far as I've been able to ascertain (and of course I might be 
mistaken), Gnus does not support IMAP. To be sure it will download mail from an 
IMAP server (I have that set up already), but that is not my use case. I have 
my inboxes (the contents of which are retrieved from the outside world by 
fetchmail) and about twenty-years worth of filed mail in a local Dovecot IMAP 
server. I don't want my mail client (whatever I end up using) to make its own 
local copy of my mail -- I want it to allow me to read the mail in my IMAP 
inboxes, delete it on the rare occasions that I want to do that, or file it in 
other folders on the IMAP server. Did I miss something, or am I correct in 
thinking Gnus lacks the ability to interact with an IMAP server in that way?

3. RMAIL: Again, can it interact with IMAP as above? The impression that I've 
reached is that RMAIL is adamant about having it's own local copy of things.

4. Mutt with Emacs as external editor: This is the solution I'm leaning 
towards, but I'll be sad if I can't get an all-Emacs solution working. (After 
all, I do almost everything else on my computer in Emacs.) Are there known 
pitfalls to using Mutt with Emacs?

Thank you to anyone with suggestions.

N. Jackson.