Semaphor offers team-owners the ability to set domains which will automatically be approved when a user with that domain in their username submits a join request to a team. You can set this functionality by accessing your Team Preferences and navigating to the Permissions. Select it and you should be able to set a domain within the blank field beneath the Auto Accept Join Requests row. Add the domain you wish (e.g. spideroak.com or yourcompanyname.biz) and select the back ‘<’ arrow at the top of the window to save your choice. Now, any user who submits a join request to your team using that domain will be automatically approved.
Automatically Adding Users to a Channel