When adding users to the Team Server, an invitation mail to register is automatically sent to these users. If this invitation mail for whatever reasons gets lost, it is possible to resend an invitation, so that the user will be able to register after all.
In the sidebar menu, click Users, and then clicknext to the unregistered user you want to send an invitation.
Alternatively, you can click the unregistered user's icon, and then in the sidebar click Manage.
In the Manage user menu, select Resend invitation, and then click Send e-mail.
An e-mail message with an invitation to register will be sent to the user.