BM 3.6 on NW 5.1 sp6 (with the latest updates per CJ's site as of end of

Is there such a thing as "rejecting" a packet as opposed to "dropping" it?

There is a mail server that is sending port 113 (identd/auth) packets to
our Blackberry related server (Roamail). Our BM 3.6 is dropping the
packets. Seeing how our Blackberry users are complaining about slow
delivery of email, I decided to investigate.

Port 113 is identified on the port list as "identd/auth".
Reportedly, "identd" is used by mail servers to identify the "owner"
of a connection, and is also used by hackers.

I don't want to open the port if I don't have to, so I emailed the
Roamail techs to see if they knew anything about it. They said they have
seen it. Their suggestion is that I "reject the packet" so that the mail
server that is looking to identify our Roamail server will get a reject
message. How do I do that on BM 3.6? Our setup is that we deny all and
then only open what we need.