Successful Mail Delivery Report Language change

[Tcap]

I want to change this message.
where can i do?

ty...


This is the mail system at host svr9.3x.com.

Your message was successfully delivered to the destination(s)
listed below. If the message was delivered to mailbox you will
receive no further notifications. Otherwise you may still receive
notifications of mail delivery errors from other systems.

                   The mail system

: delivery via dovecot: delivered via dovecot service