Panelist emails aren´t accepted - says they are invalid but they are not

Description
I´m trying to add panelists to a webinar that are external to our organization, but their valid emails are coming up as invalid and I can´t add them.

Error?
Invalid email

Hi @emily1, welcome :wave:

Does this behavior happen when you add these emails into the web portal/UI? Is the behavior the same between the web portal for the webinar settings and the API?