I am sure I am the first one, but I have found that using a .TLD of more than 5 characters will not work when setting up the email settings for CBD. I found this out as I use .system for certain things. As you can see from my screenshots with 5 characters it is fine, but once I enter the 6th character you get the error. I found it doesn't actually confirm the domain it is simply just a character limit issue with the TLD.
I am curious how I would submit a bug for this since I am on the free 25 license edition.