Fehler 550, wer kann mir helfen?

[mirko]

unrouteable address ist E-Mail-Adresse nicht mehr korrekt

[danym]

Hallo was heißt diese Fehlermeldung?

Was muss ich machen?

Gruß danym

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 mail system

<xxxxxxxxxxxx>: host mx.freenet.de[xxxxxxxxx] said: 550 unrouteable
address (in reply to RCPT TO command)