Email address opted out in filters causes Bad Server Response

[yuri]

Issue: https://github.com/espocrm/espocrm/issues/1024

[tanya]

Filtering by this field is not supported

[Dmitry]

I have added "Email address is opted out" to the Contacts Search Filters through Layout Manager. But when I am trying to run a search in Contacts with this filter on, I always get a "Bad server response" message. Why is that?