Kaspersky blocks webforms

Kaspersky blocks webpages as dangerous even though there are no harmful parts on it.

Message:
Von Web-Anti-Virus blockiert.

Grund: Gefahr eines Datenverlustes

Erkennungsmethode: heuristische Analyse

Example: https://www.post-sv.de/csaprog/kontaktformular.php (it is a simple contact form).

What causes the blocking and how can I modify my web pages in a way Kaspersky does not classify them as dangerous?

It would be great if somebody has hints for me.

Regards
Bernie