"Connection" refers to the entire sequence of client/server interaction from the initial establishment of the network connection until its termination.
Could I compare it with login complete?
That's like saying "can I compare a drive in my car to starting the motor".
The definitions of "connection" and "session" in RFC 3501 are fairly specific. I believe that any additional definitions would only make matters more complicated instead of less complicated
If the IMAP client which uses c-client wants to show the list of mails from all of the mailboxes after login complete, then user could select the mail interested, does it mean that there must be multiple "connections" (multiple login's) in order to maintain multiple mailboxes to be SELECT'ed, so that the data in c-client's cache could be used later.
Only one mailbox is SELECTed at a time, and c-client only caches data from the currently SELECTed mailbox.
You can have multiple MAILSTREAMs open, each with a separate mailbox selected. It is your choice whether you want to do that or to go through each mailbox one-by-one.
HOWEVER!!!!!
It is an exceedingly poor idea for a client to attempt to list messages from all mailboxes. The list of mailboxes may be extremely long with long servers. You will run out of memory and disk space on your client long before you complete gathering the entire list.
It is also a misuse of IMAP. The entire reason why IMAP has all these features to collect individual data items is so the client can access data on demand by the end user, and not have to download everything at startup.
The best way to implement an IMAP client is to pretend that you have a basic DOS machine with 640K RAM, a 20MB hard drive, and a 2400bps modem; and to assume that the user has 10,000 mailboxes each with 100,000 messages and each message is 500K. You wouldn't even think of trying a mass download in such an environment. Instead, you would get only that data that is needed at that point in time.
-- Mark --
http://staff.washington.edu/mrc Science does not emerge from voting, party politics, or public debate. Si vis pacem, para bellum.
