(Contact) Flags emails using free domain/email service

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A good idea I have seen is checking if the maintainer email use one of the following service

[
  'gmail.com', 'yahoo.com', 'hotmail.com', 'outlook.com', 'live.com',
  'protonmail.com', 'proton.me', 'mail.ru', 'yandex.ru', 'qq.com',
  '163.com', 'aol.com', 'icloud.com', 'zoho.com',
]

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There is a need to think where do we exactly push this information (flag or whatever). Maybe we should consider extending Contact at some point.