Re: IMAP4 List Command Extensions

[Arnt Gulbrandsen <arnt@xxxxxxxxxxxxxxxxxxx>]

Let me step back. AFAICT, there are two approaches to this:

1. Client sends LIST. When an interesting LIST response arrives, it 
sends a STATUS command. As the STATUS commands' responses arrive, the 
client has the information it wants.

2. Client sends LIST with some extension. For each mailbox matching the 
supplied pattern, the server does the same work that STATUS would do, 
and sends the result in a LIST response.

Do I understand it correctly?

Alternative 1 has a cost of two roundtrips, plus traffic costs for the 
LIST responses and for the responses to STATUS, plus CPU costs for 
LIST, STATUS and quite a bit of parsing.

Alternative 2 has a cost of one roundtrip, plus traffic for the LIST 
responses, plus CPU cost for LIST including STATUS.

If we assume that there's 100 LIST responses and 10 interesting 
mailboxes, then 1 costs one roundtrip more and 2 has 90 unnecessary 
STATUS processings and 90 unnecessary transmitted UIDNEXT/UIDVALIDITY 
pairs. (And of course, a client that implements 2 has to implement 1 as 
well, or else it won't work with plain servers.)

Hm. I suppose I must misunderstand terribly, because I cannot see any 
appeal in 2 at all.

Arnt