"Test diacritics in mailer" & v.0.23

**Describe the bug** A clear and concise description of what the bug is. **To Reproduce** Steps to reproduce the behavior: 1. Go to '...' 2. Click on '....' 3. Scroll down to '....' 4. See error **Expected behavior** A clear and concise description of what you expected to happen. **Screenshots** If applicable, add screenshots to help explain your problem. **Stacktrace** If applicable, add the error stacktrace to help explain your problem. **Extra data (please complete the following information):** - Device: [e.g. iPhone6, Desktop] - Device OS: [e.g. iOS8.1, Windows 10] - Browser: [e.g. Chrome, Firefox, Safari] - De