JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
I checked one of the sub-user you created (firstname.lastname@example.org) and I was able to see on our mail log that there is no invitation email sent. Can you try to remove the sub-user and re-add again the email and see if the email will be sent now? If the issue still persists, the your sub-user can always create a Free Account in JotForm using this link https://email@example.com. Just replace the email value in the URL for your other user.