Secondary mail server collects the spam

[cubera]

Hello...

I've setup two mail servers with the Toaster script.
The primary mail server has MX 10 and the backup mail server has MX 50. The problem is now that the backup mail server accepts the messages that are rejected by the primary and hold them for a few days. This use quite a lot of space and resources just for junk.
Is there a simple solution for this kind of problem?

Many thanks for your ansers.

- dom