I tried to do an integration with SendGrid in an account which I had a not verified email address.

I could check the error message while inspecting the network (could have a better error message on UI), and it said that it must be a verified email.

I added a verified email in my account, keeping the unverified one. Even tho selecting the verified email on the publish screen, I keep getting the same error.

Removed the integration, created a new token, chose the verified email, same error.

Only way to pass this was to remove the unverified email from SendGrid account.