sieve, pigeonhole; reject message

[dovecot-user]

Hello everybody.
I use the version of dovecot 2.3.0.1 and postfix 3.3.0 on my test 
computer. Postfix pass incoming messages to Dovecot via the LMTP protocol.
I want to understand how to fine tune the "reject" action in sieve-scripts.
The task: in my installation I use the translation of a set of aliases 
into the (hidden) target email address inside postfix (postfix 
directives: canonical_classes = envelope_recipient; canonical_maps = 
hash://etc/postfix/canonical), so in dovecot the mails fall into one 
mailbox; However, the original headers (for example, the alias of the 
recipient) can be extracted with sieve scripts (the "Received" header). 
In my case, when I use the "reject" action in the sieve script, dovecot 
generates a message to the sender with the text: "Your message to 
<hidden at domain.tld> was automatically rejected ..", but this behavior 
opens the address to the sender of what is hidden behind the alias.
Is it possible to redefine the text of the reject message using the 
extracting values ​​from the "Received" header so that the email address 
hidden behind the alias does not appear there?
Or some other way to customize the reject-message?

Thank you.