Mails send from the backend do not meet requirements for domain authentication

[RAYs3T]

Email send from the backend is missing some authentication requirements. This leads into false spoof detection in some mail clients.

For example in ProtonMail:

This is most likely caused by using the old domain: open-book.org as sender in the mails.

[lifenautjoe]

Hi Kevin! Thanks for letting us know. We'll fix :-)