All messages are recognized as spam!

Haven’t changed anything in 5 months.

But now I deactivated ALL plugins, activated a standard theme “Twenty Fifteen” but that didn’t work.

start – Formular
<label> Ihr Name[text* your-name] </label>
<label> eMail[email* your-email] </label>
<label> Ihre Nachricht an uns[textarea your-message] </label>
[submit “Absenden”]
end – Formular

start – Settings
To: my Mailadress
From: [my Name] <my mailadress>
Subjekt: Message from my Site
additional Headers: Reply-To: [your-email]
end – Settings

start – message text
Nachrichtentext:
[your-message]

—
Diese E-Mail wurde von einem Kontaktformular von meiner Website gesendet
end – message text

Unfortunately, the plugin does not have a debug function, and the Firefox developer tool did not help me.
I’ve tried different email addresses, but no success.