554 invalid DNS PTR resource record

I recently setup a server for a webshop with prestashop. The problem i have i cannot send email from the server, when i look into /var/spool/mail i see a lot of error like this:

----- The following addresses had permanent fatal errors -----
<email@domain.tld>
(reason: 554-kundenserver.de (mxeue006) Nemesis ESMTP Service not available)

----- Transcript of session follows -----
... while talking to mx01.1and1.fr.:
<<< 554-kundenserver.de (mxeue103) Nemesis ESMTP Service not available
<<<...

554 invalid DNS PTR resource record