DeepSeek didn't always have a whitelist. At some point they went crazy due to spam, started requiring Chinese phone numbers only, and then loosened it to an email domain whitelist. (IIRC)
If you try to sign up with a domain they don't support, they tell you something like "please use a popular email provider like gmail"
If you try to sign up with a domain they don't support, they tell you something like "please use a popular email provider like gmail"