* If the email middleware does not send mails, it will give a warning
similar to sentry middleware
* Eliminated GrapphQLClient in one more test
* Rename code => nonce
Sending a mail with further instructions even if the email is invalid
seems to be a good practice: A potential attacker will not now if a user
has an account under that email address. If a user does not remember the
email address, but has control over the other mail account, she will get
feedback that this mail account is incorrect.