Web application that lets you test if your domain is vulnerable to email spoofing.
This application is designed to be used as a service. However, if you want to host this yourself, do the following:
git clone https://github.com/bishopfox/spoofcheckselftest.git
cd spoofcheckselftest
pip install -r requirements.txt
./selftest.py -s
Then visit http://localhost:8888 in a web browser