I need your help (ausfuhranmeldung) (Dresden)

Dear All
I want to send two invitation letters via DHL to Iran but they told me I need to get ausfuhranmeldung (export declaration)!
I have tried to find it out but I could not1:((
Do you know how can I get it?
Is there any company which do it for me?
It is really urgent because my friends have an appointment with embassy in 20th of Feb!
Best
Narsis