Send emails non-confidential to external recipients by default

[armhub]

We noticed that for some new users it is confusing that you have to enter a password when sending an email to an external recipient. In order to have a smooth onboarding for a new customer we want to send non-confidential by default.

Nevertheless, by clicking the lock symbol the email draft can be switched to confidential. Similarly in the settings the default can be changed.

Test notes

• Create a new account
  • Verify that external emails are sent non-confidentially by default in the settings (Settings -> Email -> Default delivery -> Not confidential)
  • Verify that, when drafting an email to be sent externally, it is also not confidential
• Verify that any existing user is not affected by this change

[murilopereirame]

Closed by MR 584