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