1. Google Apps
2. https://www.zoho.com/
3. https://www.rackspace.com/email-hosting/webmail
3. https://www.fastmail.com/pricing/
4. https://www.pobox.com/pricing
5. https://qiye.aliyun.com/
6. https://qiye.163.com/
7. https://exmail.qq.com/