Thank you very much for the quick reply.
But this is not my problem.
No matter if I use the code
[text BC default:get] or
[text BC default:get default:post_meta "BC"]
everything is fine.
As soon as I integrate into the code hidden
[hidden text BC default:get] or
[hidden text BC default:get default:post_meta “BC”]
the field is not visible in the form but the link …./?BC=4711 so the 4711 do not appear in the field BC when I get the mail.
Is there another possibility not to show the field BC in the form, but still to get the 4711 in the field BC with the mail I receive.