LinuxQuestions.org - qmail bounce back mails

My introduction : im a Sr. Sys Admin (windows and Linux)i relectently say that im not new to linux , but not a expert,yet im facing some problem in qmail.
i have Centos linux distribution with qmail with only SMTP not POP3 service ON,basically through our own developped(ASP.NET)application it sends lot of mails by their senders(leads) to their respective customers via this Qmail box.
my questios are :

1)some times mails stuck in a queue can i configure it for faster delivery.
2)can we catch bounced email messages and let these mails not to acknowledge (MAILER-DAEMON) to the the sender , considering these sender email ids are not at all local and not known(defined) to qmail server(these are from different domains and carrying different ids and sending multiple mails through qmail SMTP connection), Is there any procedure of defining them in qmail so that we’d have better control over returned and bounced mail e.g RELAY/REJECT/ERROR TO /DISCARD (can USER/HOST Masquerading help in this)?

3) can we validate the sender by making entry in /home/vpopmail/domains/ e.g leadingedge-mtg.com ?
4) can I make same entry in /etc/tcp.smtp (as in sendmail /etc/mail/access file we can define ) ?
5) can mail routing/redirection possible to different domain except our default

deepak jain

Leo Technosoft