Change
[email* email watermark "E-Mail-Adresse"]
[mailpoetsignup mailpoetsignup mailpoet_list_5 default:on]
to
[email* your-email watermark "E-Mail-Adresse"]
[mailpoetsignup mailpoetsignup-333 mailpoet_list_5 default:on]
The field name for email must be your-email
.
The -333
in there mailpoetsignup code helps the shortcode function diversify what it’s reading. It can be any random number and it will still work.
The mailpoet_list_5
of the mailpoetsignup code specifies the list the user should be subscribed to. It is set when you check the box in the form when creating the field.
Also, if you want to capture their names into the subscription, change these:
[text* your-first-name watermark "Vorname"]
[text* your-last-name watermark "Nachname"]
So, for clarity, I believe your whole form should look like this:
[text* your-first-name watermark "Vorname"]
[text* your-last-name watermark "Nachname"]
[email* your-email watermark "E-Mail-Adresse"]
[text betreff watermark "Betreff"]
[textarea your-message watermark "Deine Nachricht"]
[mailpoetsignup mailpoetsignup-333 mailpoet_list_5 default:on]
[submit "Senden"]