[Feature] Domain AllowList Functionality

[CaoMeiYouRen]

Is your feature request related to a problem? Please describe.
Currently, the system only supports a Domain blocklist to prevent certain domains from receiving messages. However, there is no functionality to specify a Domain AllowList. This can be frustrating when we want to ensure that only specific domains are allowed to receive messages, enhancing security and control over the email distribution.

Describe the solution you'd like
I would like to have a Domain AllowList feature that allows us to specify a list of domains that are permitted to receive messages. This would work in conjunction with the existing Domain blocklist, providing more granular control over the email distribution process.

Additional Information

• This feature would help in scenarios where we need to restrict email delivery to a specific set of trusted domains.
• It would enhance security and ensure compliance with organizational policies.