I created customized rule to reject certain recipients which I hooked
to SLocal_check_rcpt:

R$={Lista}@mydomain.it $#error $@ 4.2.2 $: Mailbox full

This rule works but I don't know because SMTP error code is dsn=5.3.0
553 while I specified 4.2.2
You can see text message is ok: Mailbox full

ERROR:

ruleset=check_rcpt, arg1=<acini@mydomain.it>, relay=localhost
[127.0.0.1] (may be forged), reject=553 5.3.0 <acini@mydomain.it>...
Mailbox full