You're not using Gmail or G Suite but still want to get the value using Docsify.
This is a quick guide for you.
(Here we'll use an Outlook email account as an example, but you may use this guide for any other email provider: Zoho, Hotmail, Yandex, and so on.)
Create a new Gmail account. For example - "firstname.lastname@example.org." Don't worry it's free.
Go to Settings - Accounts and Import - Add another email account
Choose the Name and enter your Outlook email address.
Enter SMTP server and port number.
Please use a Google search if you need to find this data. For example, for Outlook you can find this data here.
Enter the confirmation code, which will be sent to your Outlook account.
Go to Settings - Accounts and Import
And choose your Outlook email as default.
So now you can send Outlook emails from the Gmail interface and your emails will be tracked via Docsify.
Go to Outlook - Settings - Accounts - Forwarding
And choose your Gmail account.