Only allow bcc mails for pupil mails

[annkatrinkuessner]

As
data protection commissioner

I want to
have the "Sichtbar" Button hidden when sending e-mails to pupils (participation confirmation)

In order to
reduce the risk of leaking pupils e-mail addresses.

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Given
a logged in admin

When
sending out participation confirmations to users

Then
he should only have the option to send out BCC Mails to students.