Apparently the Miro server is unreliable and gives falls negatives. It seems to work now.

Hi @Johannes Kingma 

Thank you for reaching out! If you're receiving an error about invalid email addresses when trying to invite people to a board, it could be due typo errors. Even small errors like extra spaces or missing characters can trigger the invalid email message.

If everything looks correct and you're still seeing this issue, try using the shareable link option to invite users.

Since it seems to be working now, we'll consider this solved. However, if the issue persists, feel free to reach out to Miro support for further assistance.