This is the mail system at host rescopa.com.

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                   The mail system

<[email protected]>: host mail.notlimited.com[207.135.120.100] said:
    550 <[email protected]>, Sender unknown (in reply to MAIL FROM command)
Reporting-MTA: dns; rescopa.com
X-Postfix-Queue-ID: BAC763E2
X-Postfix-Sender: rfc822; [email protected]
Arrival-Date: Tue,  8 May 2018 19:06:05 +0000 (UTC)

Final-Recipient: rfc822; [email protected]
Original-Recipient: rfc822;[email protected]
Action: failed
Status: 5.0.0
Remote-MTA: dns; mail.notlimited.com
Diagnostic-Code: smtp; 550 <[email protected]>, Sender unknown