The mail does not works

I have send the message to
Then I’ve got this message

Delivery to the following recipient failed permanently:

Technical details of permanent failure:
Google tried to deliver your message, but it was rejected by the server for the recipient domain by [].

The error that the other server returned was:
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 y4si3522186lbm.196 - gsmtp

@astrosl - I’m not sure why this happened. It seems to work properly for others and we’ve received emails at that address within the past hour.