Implement email functionality

[jobrachem]

• configuration for a mail account in secrets.conf
• html text
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class MailMan:

    def __init__(self, sender, ...):
        self.sender = sender

   @classmethod 
    def from_secrets(cls):
        ...

    send_mail(text: str, subject: str, receiver: Union[list, str], response_address: str, attachment: fileobj)

• Potentiell down the road: Admin-Seite für custom Email-Versand.
  • Finished / Aborted / Expired / Evaluierung bestimmter Input-Elemente

[jobrachem]

Closed in commit 925fae2779ab0bc7f557da498f2e125e5e77b7ae