Here is how you edit the Email Groups
Setup tab: PassTracker tab: Terminology tab: 'Tag Customer to Groups for Emailing' field.
Choose the last option 'Edit...' and you can add more there.
Add your new group name here. In my case it is 'Other Stuff'
Click on the Bulk Emailer button.
Then when I return to the bulk emailer, I see a new group listed.