performance issue (imap spool on san)

Michael Loftis mloftis at
Wed Jul 26 17:45:52 EDT 2006

--On July 26, 2006 9:31:40 PM +0200 Daniel Eckl <deckl at> wrote:

> Hi Michael!
>> Thunderbird is NOT an IMAP client.

> The first time you open a large IMAP folder is not very fast, I have to
> admit, but I didn't find any other comparable IMAP client without this
> problem. Perhaps there are some, but I didn't try them because of the
> lack of other basic email features.

This is why they aren't IMAP clients.  IMAP servers make all manner of 
searching, sorting, retrieval, and storage options completely available to 
the client, without having to download even all the headers.  This is why 
Mulberry, Pine, Mutt, and Kmail are so much faster.  If TBird would just do 
that instead of insisting on blindly attempting to download all the headers 
and performing all sorting and searching on the client.  TBird and most of 
the others have their roots and brains seated back in the POP3 dark ages 
near as I can tell and that's how they treat all mail stores.  IMAP allows 
the clients to easily ask for threaded views (unless you turn the index 
options off or something like that) from the server, as well as partial 
sets of headers in batch.  This massively speeds things up when you're on a 
modem, or working with large mailboxes, or mailboxes you only occasionally 

I'm not trying to start a flamewar either, I'm stating the observed 
behavior.  They're not IMAP clients.  They speak IMAP but they make no real 
use of the protocol.  I really do wish there were more better clients out 
there, there aren't.  I totally agree with you there that Pine and Mutt are 
not a replacement for a GUI client.  I've never used Kmail extensively 

> Anyway: I'd happily listen to other suggestions for full featured
> graphical IMAP clients which could be better than thunderbird. There
> surely are things in thunderbird which could be a lot better! I just
> need an alternative which I was not able to find yet.

I haven't found one other than Mulberry either.  It seems developers widely 
assume you're not on a modem anymore, which for me is all to often not the 
case.  It's faster for me to use SquirrelMail, IMP, or Horde than to use 
TBird when I don't have access to Mulberry.

The size in MB of the folder has little to do with IMAP client speed, it's 
mostly the number of files.  Older versions of EXT3 (before they added 
directory hashing support) had pretty terrible performance in this regard. 
I don't use Ext3 much of anywhere anymore but I know there are some 
documents on how to enable that in l
later model Linux kernels.  It may or may not help your mail spool 

It's doubtful TBird/etc will ever load a mailbox with 20-30k+ messages in a 
very fast manner on first open unless they start to implement and make use 
of the IMAP extensions for partial loading combined with a local header 
cache as the view is scrolled.

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