Mailgoose is a web application designed to help users verify the accuracy of their SPF, DMARC, and DKIM email configurations. Developed by CERT Polska, it supports Polish institutions in setting up their domains, thereby reducing the risk of email spoofing. The application relies on tools like checkdmarc and dkimpy to perform these checks effectively. For those interested in contributing, Mailgoose encourages both suggestions for improvements and pull requests for new features or code enhancements. Contributions automatically fall under the BSD 3-Clause License, meaning no additional agreements are required. The project also emphasizes code quality by using pre-commit hooks to run linters and format the code before commits. Users can set this up locally and run tests with simple commands provided in the documentation. Building documentation involves creating a virtual environment, installing necessary requirements, and generating HTML files. The instructions for this are straightforward, guiding users step-by-step through the setup process. Overall, Mailgoose is a practical tool for ensuring email security configurations are correctly implemented.