Additional email addresses SPAM filtering

Hello

I have a Virtual Server with multiple child Virtual Servers. On the parent Virtual Server I have a User which is used for E-Mail.

This user also has Additional email addresses configured in the format @domain1.com, @domain2.com etc.

Is it possible that with this setup, the SPAM filtering isn’t working properly? Reason for asking is that there is quite a lot of spam which is received over one of the child Virtual Servers and these E-Mails also have a rather low SPAM score which is weird.

SYSTEM INFORMATION
OS type and version Debian Linux 10
Virtualmin version 7.5