Mail Sending Problem for Bro

Hello, everyone!
I am trying to Bro IDS as a simple IDS. Now, I want to use the MAIL Notice feature, but I am stucked here. I redefined Notice::emailed_types to add my interested Notice::Type, and installed sendmail program, which worked well through command-line usage. But it still can not work any way.
Maybe I have made some wrong settings, but how can I get debug information of mail processing? Or, are there any special settings I may forget to do? Your help would be appreciated.