You can have multiple emails attached to a GitHub account. Sometimes instead of creating a new GitHub account for work, someone on your team will just attach th

You can have multiple emails attached to a GitHub account. Sometimes instead of creating a new GitHub account for work, someone on your team will just attach their work email to their main GitHub account. Then if you set up GitHub oauth on a SaaS, and configure it to allow anyone with an email on your domain, most of your team members will be able to sign up. But for the person with the multi-email GitHub account, it will usually fail. It gets even messier when there are invitations involved.