Looks like a bad email.  Received the following:

***
Delivery to the following recipient failed permanently:

    httrack@httrack.com

Technical details of permanent failure:
Google 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: 553 553 5.7.1 <httrack@httrack.com>... Account deprecated,
please use 'httrack2-at-httrack.com' (state 14).
*** END

httrack2@httrack.com was not rejected - yet.