email error question

[hopper]

what does this mean
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This is an automatically generated Delivery Status Notification

Delivery to the following recipient failed permanently:

****

Technical details of permanent failure:
PERM_FAILURE: Gmail tried to deliver your message, but it was rejected by the recipient domain. We recommend contacting the other email provider for further information about the cause of this error. The error that the other server returned was: 550 550 Requested action not taken: mailbox unavailable (state 14).
[/code]

[Conmiro]

It means that the email adress was either spelt incorrect or does not exist.
Edit:
I get that alot when I type to fast.