Postfix : mail loops back

[vincentthe]

When sending mail to a domain which should be deliverd to a user (catch-all for user ds2_w3_vincent) the following error occurs. In which direction should I look?

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This is the Postfix program at host ds2.tt-hosting.nl.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to <postmaster>

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

The Postfix program

<ds2_w3_vincent@ds2.tt-hosting.nl> (expanded from <info@kassa-tv.nl>): mail for
ds2.tt-hosting.nl loops back to myself


Final-Recipient: rfc822; ds2_w3_vincent@ds2.tt-hosting.nl
Original-Recipient: rfc822; info@kassa-tv.nl
Action: failed
Status: 5.0.0
Diagnostic-Code: X-Postfix; mail for ds2.tt-hosting.nl loops back to myself

[till]

Please add:

ds2.tt-hosting.nl

at the end of the file /etc/postfix/local-host-names and restart postfix.