Patches for the mailing list... pull requests for you
submitGit is a step in trying to make the process easier. If you create a pull request on github.com/git/git, submitGit can close it for you by correctly formatting it as a series of patches, and sending it to the mailing list.
The patch review stays on the list - but at least you no longer need to learn a whole new method of email to submit your improvement to Git.
submitGit is set up to allow you to send test messages to yourself - all that requires is that your email is verified on GitHub - but when you want to mail the Git mailing list for real, there are a few extra requirements: