The 30-second delay you see is effectively a quality of implementation issue.
The MTA delivering the message into the mailstore isn't required to do that in any specific time: It can take 0.01 seconds or it can take 15 seconds, depending on luck and system load. Similarly, the IMAP server isn't required to notice the new mail at once. It's permitted to check every second or every minute, or alternatively it may be notified by the delivery agent. In either case the SMTP/LMTP/POP/IMAP requirements are met, and if you want to write an IMAP client that interoperates well with the existing, deployed servers, you should try not to depend on anything else. <truism>If you use a better server, you get better overall service.</truism> The other approach I suggested should be faster (but hardly anyone implements it yet). ftp://ftp.ietf.org/internet-drafts/draft-shapira-snap-04.txt is the current draft. --Arnt
