[maemo-users] Diablo's Modest/Email

From: Theodore Tso tytso at MIT.EDU
Date: Wed Sep 10 00:11:51 EEST 2008
On Tue, Sep 09, 2008 at 01:53:40PM -0600, Mark wrote:
> Anyway, I didn't say that IMAP was a "resource hog" in the grand
> scheme of computing, only in comparison with POP3.

It really depends on how the IMAP/POP3 server was implemented.  Some
POP3 servers are implemented optimizing for the case where all of the
mail messages are downloaded, and then deleted; so if you download all
of the messages, but only delete a few, it could be quite expensive if
the POP3 server stores the mailbox as a single file, and deletes
require copying all of the messages which are _not_ deleted.

In contrast, if your IMAP server is implemented to use some kind of
back-end database, or a Maildir directory, a particular implementation
of IMAP could be more performance than a particular implementation of
POP3 protocol.

It's also true that IMAP has some extra operations that allow for
partial download of just the header information, for example.  If a
POP3 client implements this by downloading *all* of the mail messages
each time you connect, without caching the downloaded mail messages
due to local space reasons, in theory POP3 could be less efficient and
end up impacting the server more.

On the other hand, IMAP has some optional SEARCH capabilities which
could impact the server; but the server doesn't have to implement said
search extensions.

So it's a lot more complicated than saying categorically that IMAP
always uses more server resources than POP3, or vice versa.  A lot
depends on how the client was implemented, how the server was
implemented, and what sort of user functionality is desired.


					- Ted

P.S.  Something I very much like is a program called "mbsync",
available at http://isync.sourceforge.net.  This will use IMAP4
download a local copy of all of your mail message to a local laptop or
tablet, in a Maildir directory on local disk (or flash storage).  This
allows you to read your e-mail messages while disconnected, without
needing access to the network.  After you mark messages as deleted,
the next time you synchronize your local Maildir store with your IMAP4
mailbox, it will delete any messages marked as deleted, and then
download any new messages.  Since the messages aren't deleted on the
IMAP server, if your tablet gets lost or destroyed, the messages
aren't lost, since there is a copy safely on the IMAP server.

Yes, you can in theory do this using POP, but this particular
implementation only does it for IMAP.  It's open source --- people who
want to implement this for POP are free to do so.  In general, I find
the attitude of the original requester who seemed to expect that other
people implement software for his own convenience to be a little
annoying.  If there's something you want that isn't yet implemented in
open source, either implement it yourself, or gently request that
someone who can implement do so --- or perhaps you can hire them or
otherwise give them some kind of incentive to implement the feature
for you.  Open source developers do *not* owe anything to their user
base; they implement feature requests out of the goodness of their
hearts, or because they need the feature as well.

Or, of course, you can use another solution.  I still carry around a
Palm Pilot because none of the opensource PIM applications are good
enough yet.  And I use a Blackberry because its e-mail solution is
still far superior to what is available on the Palm or N800 platform.
But you don't see me whining about how people *must* make improvements
to the N800's mail client.  I hope it will happen, but unfortunately I
don't have time to help improve the N800 mail client.  I did however,
help improve the isync project until it was good enough to meet my
needs.  That's the way open source works...  you scratch your own

More information about the maemo-users mailing list