There is Front Door Rejector function to reject invalid recipients,also it can use to blocked sender,but all return with error: 550 No such user found on the system. (CRF)

if sender rejected can be independent config file,reject with error message such as: Sender email or domain rejected by the system. I think it will be better.

SenderRejection.dat
[\S]*@outlook\.jp$$$ALL

Rejected with message: Sender email or domain rejected by the system.

CustomRejection.dat
ALL$$$no_such_persion@mydomain.com
spammerTwo@nono.com$$$validuser@yourdomain.com

Rejected with message: 550 No such user found on the system or rejected by recipents.

There are too many outlook.jp spams,even to quarantined is wasting disk space.