RT not responding to some requests

Good afternoon,
I have spent days looking on the Internet and in mail list archives and
have not found the answer to this problem. I really hope someone can help.

RT works perfectly right now if email is sent to rt@aaa.com (example).
However, we have 2 other email addresses that forward to rt@aaa.com. The
other 2 addresses are rt@bbb.com and rt@aaabbb.com (due to a company
merge). If email is sent in to rt@bbb.com or rt@aaabbb.com RT will get
the ticket and record it in the queue but will not send out an email
auto response. There isn’t even a record in the history that an email
was sent out.

I don’t know if it has anything to do with it but the “To:” line in the
tickets do reflect where the email was originally sent to, such as
rt@bbb.com or rt@aaabbb.com. Not sure if that matters but I’m trying to
give all the information i can.

Has anyone seen anything of this nature before that can offer any help?
If you have questions please ask as I am desperate to find a solution.
Thank you for your time.