Responsible acc. Article 4 (7) of the EU General Data Protection Regulation (GDPR), as well as Article 5 of the Telemedia Act (TMG) and Article 55 of the Interstate Broadcasting Treaty (RStV):

Frank Siebert
Ingenieurb├╝ro Frank Siebert
Im Krautgarten 20
69207 Sandhausen
Subject:'[] Your Subject'
Public Key:

Information: I also keep getting spam emails. I avoid opening it for the known security reasons.

You can ensure that the mail is opened by using the subject prefix given above. For secure mail communication, you can encrypt the mail with my public key and sign it with your PGP key.

VAT identification number: Requested last year but not yet received.