extracted from RFC 3501 :
<< The server completion result response indicates the success or failure of the operation. It is tagged with the same tag as the client command which began the operation. Thus, if more than one command is in progress, the tag in a server completion response identifies the command to which the response applies. There are three possible server completion responses: OK (indicating success), NO (indicating failure), or BAD (indicating a protocol error such as unrecognized command or command syntax error).
Maybe this permit some IMAP server to reply faster to the user commands ? Although there are not many servers that implement that capability.
I've never seen any. Have you?
--Arnt
