Ubuntu – How to delete contents of sendmail’s deferred queue

I'm testing a moderately high volume (eventually possibly up to 100,000 or so) of emails in a script I'm writing. I'm generating a list of emails that will end up in one of my accounts and having the script process them, and it's working pretty well, but for right now I just want to make sure sendmail is receiving the right number of requests without actually sending any mail.

I've got sendmail turned off and when I run the script I get the expected number of requests in the deferred queue (when I run mailq I get the right number of requests marked "(Deferred: Connection refused by [127.0.0.1])").

I know if I had sendmail running and wanted to delete the messages that were actually queued I could delete the contents of /var/spool/mqueue (I'm on an Ubuntu 10.04 LTS machine). However with sendmail turned off there's nothing in mqueue, and when I turn sendmail on it starts to send all of those emails, I can't delete them from mqueue as fast as sendmail processes them.

Is there any way for me to delete them from the backlog with sendmail turned off so I don't accidentally send some? Right now if they get sent it's no big deal (again they all end up in my mailbox), but I would like to test it with an actual set of test data, and it's important that those emails not get inadvertently spammed.