In order to use Docsify for your personal emails or Gsuite aliases you need:
1. Create an alias:
If you use Gsuite account, take a look at this article
If you use other non-Gsuite providers, such as Outlook, Zoho, Yandex and so on, take a look at this article
2. Add Docsify to your Main account
When you activate your account choose the main one
Once you do this you will be able to use Docsify with all your personal email accounts that are connected as aliases.