e-mail address forward only

I am the administrator of office365 for nonprofits of our church.
We use the domain pg-alkmaar.nl with multiple email addresses created. Many users forward emails to their private email address and never log in.
Now we are dealing with the fact that these users are not seen as active users and we do not meet the requirement of 85% active users.
In more simple configurations like DirectAdmin it is possible to create forwarders. Mails send to these addresses are forwarded to an external address. No mail can be sent with these addresses as sender.
My question is: does this option exist within Office 365? I've searched, but haven't found it yet.

And then count these forwarders as users.
I have already tried with rules, but without success.