i test the command today, and found out that it only takes 1.5 secs, nothing
change from the 5 secs result. I add the 192.168.1.10 to my /etc/hosts file,
and it drop to 0.5 secs to inject 100 msgs.

1. Question here, if the sender IP is not in my /etc/hosts, will postfix do
a reverse lookup on the IP ? If yes, means it will affect my performance,
any way to help to increase without adding to the /etc/hosts file.

although it took only 0.5 secs to inject the 100 msgs, but from the
/var/log/maillog, i noticed that for the 100 msgs to fully sent to the
cde.com from start injecting to successfully sent it took almost 9 secs.
There only a cable direct connect between 2 servers and is gigabits
connection. So from the calculation it send almost 11 msgs / sec and the is
400 KB per msg so almost 4.5MB  transfer between the 2 server, thats was way
under 1 gigabits connection throughput. i check that the user maildir from
the cde.com, the time to create the 100 msgs is only 2 secs, wheres go the
other 7 secs in between ? is it cause by the low end cde.com receiving
server ?

kindly please advice again, thanks..




On Tue, Jun 1, 2010 at 9:52 AM, Wietse Venema <[email protected]> wrote:

> Teh Kim Chooi:
> > It sounds weird to me, the 192.168.1.10 is on server eth0 network
> interface,
> > and it will be on my local etc host file, will postfix still do NSlookup
> ?
>
> The Postfix SMTP server looks up the client hostname with the
> getnameinfo() system library routine.
>
> I have attached a test program and recommend that you run it
> on the machine where sending mail was slow.
>
> ./getnameinfo 192.168.1.10
>
> See source code for instructions.
>
>        Wietse
>

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