Error, mails from form "New member" are not sent!

• The problem is that from the form builder the mails are not sent! The form has been running for a long time and until now the mails were always sent. But now it seems that the mails are not sent anymore. Other mails are sent without any problems. According to the support blog I am not the only one with this problem see --> Form not send?

Website: www.ackriens.ch

Page: "New membership" from SP Page Builder

• Part 2 Registration with form
• Form Builder (registration form)