qmail slow

[girishg@xxxxxxxxxxxxxxxx]

hi all ,

I am running qmail and all the mails to be delivered is routed from a windows 2000 server my probelm is all my clinets say my mail server is slow and some times they are not even getting mails .. 

but when i try 
echo me@xxxxxxxxxxxxxxx | /var/qmail/bin/qmail-inject
it get delivered soon 


1 Mar 2004 22:14:05 GMT  #6359941  11144  <mycampaign@xxxxxxxxxxx>
        remote  beveradds@prichanged .com
1 Mar 2004 22:14:14 GMT  #6359964  10949  <mycampaign@xxxxxxxxxxx>
        remote  christina@xxxxxxxxxxxxx

many mails are queued like this in remote queue .. 
some around 1000 mails are there like this ..
my control files are

[root@changed control]# cat concurrencyincoming
400

[root@changed control]# cat ../supervise/qmail-smtpd/run
#!/bin/sh
QMAILDUID=`id -u qmaild`
NOFILESGID=`id -g qmaild`
MAXSMTPD=`cat /var/qmail/control/concurrencyincoming`
exec /usr/local/bin/softlimit -m 2000000 \
    /usr/local/bin/tcpserver -v -R -l 0 -x /etc/tcp.smtp.cdb -c "$MAXSMTPD" \
        -u "$QMAILDUID" -g "$NOFILESGID" 0 smtp /var/qmail/bin/qmail-smtpd 2>&1



[root@changed control]# cat ../supervise/qmail-send/run
#!/bin/sh
exec /var/qmail/rc



[root@changed control]# cat ../rc
#!/bin/sh

# Using stdout for logging
# Using control/defaultdelivery from qmail-local to deliver messages by default

exec env - PATH="/var/qmail/bin:$PATH" \
qmail-start "`cat /var/qmail/control/defaultdelivery`"



why mails remains in remote queue  ?
why qmail seems to be slow for customers ?

any clue , idea to help me please ?

Girish