Catch a rejected message ?

[White, Daniel E. (GSFC-770.0)[AEGIS] via users]

We are using SpamAssassin 3.4.6-1 with Postfix 3.5.8-4 on RHEL 8

We are seeing occasional blocked messages that say “milter-reject” with a spam 
score of 8

Is there a way to capture the offending messages to figure out the problem ?

Thanks