Returned mail: see transcript for details

[Mail Delivery Subsystem]

The original message was received at Mon, 29 Mar 2021 05:57:41 +0900
from dynamic-adsl.viettel.vn [171.224.178.84] (may be forged)

   ----- The following addresses had permanent fatal errors -----
<hf7nyc2y5jgx57n at nta.co.jp>
    (reason: 550-5.1.1 The email account that you tried to reach does not exist. Please try)

   ----- Transcript of session follows -----
... while talking to aspmx.l.google.com.:
>>> DATA
<<< 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  https://support.google.com/mail/?p=NoSuchUser b11si12645356plh.216 - gsmtp
550 5.1.1 <hf7nyc2y5jgx57n at nta.co.jp>... User unknown
<<< 503 5.5.1 RCPT first. b11si12645356plh.216 - gsmtp
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