Throttling mail sending in Postfix

I have a client that needs to send some bulk email (no really, they are
not spammers, it's a legitimate research contract) but the software that
generates the mail just blasts everything to the smtp server (no
batching, timing, throttling).

Is there any reasonable way in postfix to slow down, batch or throttle
the outgoing mail. I can find a transport setting about concurrency, but
I'm hoping for some better tuning options. Any ideas?

Thanks,
        Les...
Received on Tue Nov 28 11:22:22 2006