I don't think there would be any problem doing what you're wanting. You can inject the 100k messages using a script in Linux.
In your case, I recommend using Life With Qmail, which is a link in my signature below. If you're going to host a bunch of domains or if you want more features on your mail server, you can use the other lnk I'm showing there, or you can try www.qmailrocks.org.
These howtos give you more utilities to work with. The ones I think you'd be interested in are the logging features like qmail-analog, IsoQlog, and MRTG for qmail.