Post has no deliver fail return message to mailbox

Hi All
My postfix server on SLES15 SP4 has configure dovecot as imaps server and using smtps as send protocol.
it seem wortk fine to send mail to external mail system e.g: gmail / o365 and exchnage server.
but I fiund my postfix has a issue let me confused about incorrect user address.
for example: user type incorrect mailto mail address to let mail could not deliver or this some garbage character in mail address. the /var/log/mail will get system message.
but user mail box has no return message from postfix or external mail system.

the /var/log/mail message like below:

550-5.1.1 The email account that you tried to reach does not exist. Please try 550-5.1.1 double-checking the recipient’s email address for typos or 550-5.1.1 unnecessary spaces. Learn more at 550 5.1.1 Fix bounced or rejected emails - Gmail Help s187-20020a625ec4000000b0064ebd286b56si32819pfb.224 - gsmtp (in reply to RCPT TO command ))