Hvad er det lige at der sker her?

Efter at have postet et indlæg i et af spg her på exp fik jeg en mail med følgende indhold:

********
This is the Postfix program at host av-mx.acomma.com.

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

<mailrobot@exp.dk>: host hermes.acomma.com[62.61.157.246] said: 553 sorry, that
    domain isn't in my list of allowed rcpthosts (#5.7.1) (in reply to RCPT TO
    command)
*******

Hvad er det lige der sker her... - hvorfor får jeg en fejlmeddelse som om at jeg har skrevet en email??

Peter