[Mimedefang] Problems with outgoing bounce messages, unkownuser, plus to many bad files in sendmail queue

[An.H.Nguyen]

I've changed my sendmail.cf Timeout option to these values and notice that 
only a couple of bounce emails get generated (vs hundreds before)
I am not sure if the otpion "O Timeout.queuewarn.dsn=0s" is the one that 
stops sendmail from sending out those non deliverable messages....
Do you know if any of these options may cause any unwanted behavior?  I 
realize that this is a sendmail fqa but imagine if someone knows the answer 
out of the head that will be great help for me.
I still see more files in sendmail queue than reported in mailq command. Is 
there any mimedefang filter code to block these extra files from writing 
into the queue?  Thanks!

O Timeout.queuereturn=2d
O Timeout.queuereturn.dsn=5h
O Timeout.queuewarn=4h
O Timeout.queuewarn.dsn=0s