When defining a forwarding filter the expression is either a conjunction (&&) or a disjunction (||). However, the UI lists a AND/OR selection for every single atomic expression. This is misleading. It took my several months of wondering why the expression isn't working until I surprisingly realized that when selecting AND between two filters, everything is ANDed. Because I can only define one filter for every recipient, I thought I could define a filter respecting precedence (punkt vor strich / AND before OR) but actually. This didn't work.

1. The UI should show only a single select-box for AND/OR given today's functionality
2. Even better would be to respect precedence of AND before OR. I understand that this may be difficult to understand for non-logicians. But visual cues could solve this problem
3. It would also improve the situation if the forwarding rules were not keyed by recipient email.