Eric,
In my experience the local MDA is negligible. I use "cat", and even on
a fast link fetchmail still scrolls slowly past on the screen fetching
one message at a time. Maybe there's nothing that can be done because
of the IMAP protocol, but it seems like at awfully slow way to get
email.
Try this: use cat as your MDA, and measure the amount of time it takes
to download a small inbox, say 500 messages and about 1MB total. Then
compare that to the theoretical bandwidth of the link. OR maybe
download the same inbox using rsync for comparison.
Since you're using cat, it will all be IMAP/fetchmail. This will give
you some measure of the efficiency of IMAP fetchmail.
Maybe there's nothing that can be done because of the IMAP protocol, but
it sure seems like a darn slow way to get mail.
Larry (whose favorite way to get mail is still rsync)
Larry M. Augustin, CEO, VA Linux
Tel: +1.510.687.7029 Fax: +1.510.683.8680
Web: http://www.valinux.com
-----Original Message-----
From: Eric S. Raymond [mailto:esr(_at_)thyrsus(_dot_)com]
Sent: Sunday, September 30, 2001 1:20 PM
To: fetchmail-friends(_at_)ccil(_dot_)org
Cc: lma(_at_)valinux(_dot_)com
Subject: Should fetchmail default to delivering through procmail?
The most serious complaint I have received about fetchmail in the last
year
is that it's too slow downloading mail for people on laptops with
limited
time to connect. Most users, who have fetchmail running in
background,
all the time, don't notice this.
The two things that seem to slow fetchmail down are (1) the overhead
of
DNS
queries done to check addresses, and (b) the lockstep logic in the
POP3
and
IMAP drivers.
The easiest and most effective thing I could do to address the speed
problem
would be to eliminate DNS lookups from the normal mail processing
loop.
And
the most effective way to accomplish this would be to default to
delivering
with procmail rather than sendmail -- no more DNS round trip on each
message
as the listener chewcks the address given in the HELO line.
Until recently I would have rejected the idea of defaulting to a local
MDA out of hand. But I've found out that procmail actually does check
for disk full and process-table-full conditions and return a nonzero
status that fetchmail will see (and from it deduce that it should
not delete the current message). Also, I have realized that
sendmail's
mail alias expansion isn't needed in single-drop mode.
I'm thinking of changing the logic now so that in single-drop mode
fetchmail always delivers through procmail, if procmail can be found.
Can anyone see any objection to this?
--
<a href="http://www.tuxedo.org/~esr/";>Eric S.
Raymond</a>
"America is at that awkward stage. It's too late to work within the
system,
but too early to shoot the bastards."
-- Claire Wolfe