If you want to add external users, you could do so by mentioning them by email. This will send them an email with a snippet of text and instructions to register.
Here's how:
Start typing a comment (either in the extension or on the dashboard)
In your input field, type the "@" followed by the email address of the person you want to mention
You will have an option to choose the role that you want to assign to a person
When you save your comment, the user will receive an email letting them know they've been mentioned.
Only Mention
There were 3 roles you could assign to a collaborator. Now we have added a new one.
Only mention will allow you to mention people without sharing the entire Topic with them. They will receive notification on their email with a snippet of details and an option to locate it.