Double optin for newsletter registrations via check box in account

We have read the docs: here. Theoretically we should get the double optin mail in case, if we activated the business event double optin. We did activate this event for all sales channels, but when the customer use the check box in his account overview to subsribe for newsletter he doesn’t get any optin mail, but immediately added to the list of subscribers with the status active. Is it intended behaviour for this way of the subscribing for newsletter, or it is a bug or we miss something that should be also done to force double optin for the newsletter subscription via check box in the account overview of registered customer.
Our shopware version is: