Hi JoseMB,
Could you please describle more derailed about your issue?
How does the email miss?
It is difficult to find the email item in the queue directory.
After the delivery course finished, the information in the directory would disappear.
And there is no related with categorizer step, understand the the categorizer:
http://technet.microsoft.com/en-us/library/aa998977(EXCHG.65).aspx
Regards!
Gavin