smsbox sending dlr's....

Hi,

We've been using our kannel server for sending out a few large sets of
messages (around 700k)... We've been having problems though, not with the
sending to kannel, or kannel sending them out - but when messages are
rejected at the submit_sm level, ie - error code back in the submit_sm_resp,
kannel is sending back the dlr to one of our webservers to put them into a
database, the apache and mysql processes are getting hammered to death!!

I found if I cut down the maxclients / threads on apache, all that happens
is apache gets tied up completely while they are coming through and then
smsbox puts a lot of "could not post to...." in the error logs - meaning a
bit of manual work in grep'ing and re-requesting the dlr url's.

Is there a way to limit the number of smsbox processes that send dlr's out,
so - using keepalive, it will only use one apache thread? (It may already do
this, though just wondering what can be done...)

Any ideas welcome!

Bill.