In letzter Zeit erhalte ich "Mail Delivery Meldungen" ohne das ich eine Mail gesendet habe. Ist das eine neue Masche ala phishing mails? 

Ich kopiere einmal den Text einer solchen Delivery Meldung hier ein 

This is the mail system at host mailout08.t-online.de.

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

<dangela103@aol.net>: Host or domain name not found. Name service error for
    name=aol.net type=A: Host found but no data record of requested type