Database Software

Hi,

I am a new-bie to workflow and would like to know the following from this forum:
1. I have a approval workflow that sends notification emails to users asking them for approval on quotes/orders.
Currently emails are reaching the mailbox of all the users except one. It seems that the mail for a user is boncing back (no idea of the reason). We are not sure as to why is this happenning. When we put our email id instead of the user's then we get the email to our mailbox, but it doesnot work for the user? What could be the possible reason?
Some one did tell me that when notifications are sent, the workflows write a log somewhere in the UNIX box about the notification. Similarly when mails bounce back, the log is updates with reasons of boncing. I am not sure of this is right or wrong? If right then i would like to know the path where i can see the log, to find out the reason of boncing emails.

Can some one help out? Please let me know how can i achieve this log, its path and if possible is there someother way i can track this as to why this is happe'g for a particular user only.

Thx,
Nitin