Quoting Aria Bamdad <[email protected]>:
I have the same problem with my setup. I use an IBM IMAP server and after running several traces, we found that IMP tends to request specific detailed information about every mail item in the inbox at logon. When you have 1000's of messages and if your IMAP server is not local or is not super fast, this results in the slow login problem reported here. My solution to this was to set the $conf[server][sort_limit] variable (IMP configuration, Server tab) to a small number and basically turn off sorting if there are too many messages in a mailbox. Doing this, resulted in eliminating the massive request at login.
The bottleneck here is your IMAP server then, not IMP. RFC 3501 is unfortunately limited in that it does not allow server side sorting for anything other than arrival time. So to perform sorting on ANY other field requires the IMAP client to download all of the necessary headers from EVERY message in the mailbox to do the sorting on the client-side. For a disconnected client, this is a potentially brutal operation (it is especially brutal for threaded sort, since it relies on several messages headers at once). IMP mediates this by being able to cache header data, but you have to enable caching.
This is not a problem with IMP because EVERY client has to do this. You won't see this in desktop clients, however, since they can do things like download message headers in the background and cache these headers. It is difficult, if not impossible, to do this for a webmail client, however.
Exacerbating the problem is that IMP uses the c-client library to interact with the IMAP server. Unfortunately, the c-client library is known to be HORRIBLY inefficient when it comes to querying the IMAP server. To view a single header (say, for example, the "from" header) c-client downloads the entire message envelope of every message in the mailbox, rather than just the header requested. There is *nothing* we can do about this in IMP 4 since we don't control the IMAP commands being sent to the server.
So now the good news. First, many modern IMAP servers now support server-side sorting and threading (RFC 5256 - only formally adopted in June 2008). This eliminates issues related to sorting delays. Better yet, many of these IMAP servers cache the header information internally so they don't have to parse all mail messages in the mailbox every time a sort request happens. This drastically speeds up mailbox accesses.
Additionally, c-client is no longer an issue in IMP 5 since we have replaced the c-client library with a native Horde IMAP library that is magnitudes faster.
What would be nice is if IMP only requested specifics about messages that appear in the current window rather than ask for every message in the mailbox. The problem is that if a user selects any sort field other than by arrival order, then at login, IMP asks for detailed information about every mail item in the mailbox, slowing down login to a crawl.
This is (unfortunately) correct behavior. You can't sort a single "message view". To sort a mailbox requires processing *every* message in the mailbox - or else how would you determine what messages a view entails? We can work around this a bit - namely, once we get a sorted list for a mailbox, we can continue to use this sort until the mailbox structure changes. But that only provides partial relief. The only way to truly remedy this situation is to use an IMAP server that supports RFC 5256.
michael -- ___________________________________ Michael Slusarz [[email protected]] -- IMP mailing list - Join the hunt: http://horde.org/bounties/#imp Frequently Asked Questions: http://horde.org/faq/ To unsubscribe, mail: [email protected]
