I recently got a domain for all my furry accounts so I can split my main email and Furry Life apart.
The new Email I'd like to use is [email protected] , where mydomain has been replaced for confidentiality.
However, submitting this as the new Email Address just pops up a message saying "Email Address may not be used."
Is this because of the rarely used TLD ".fyi"?

If I recall correctly, you cannot use personal domains as your email because there is actually a hidden whitelist for approved email service providers that only the admins have access to.
This is to obviously there to curb throwaway emails for spam accounts, so your only option is to use one of the more common email service providers.

thegreatwolfgang said:
If I recall correctly, you cannot use personal domains as your email because there is actually a hidden whitelist for approved email service providers that only the admins have access to.
This is to obviously there to curb throwaway emails for spam accounts, so your only option is to use one of the more common email service providers.

It isn't a whitelist, it's a blacklist
custom domains can very much be used, my own email here is on a custom domain
I can't see the blacklist myself but I can escalate it to an admin if you'll send me the domain in a dmail