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.)
Step #1 Create a new Gmail account. For example - "firstname.lastname@example.org." Don't worry it's free.
Step #2 Go to the Gmail Settings / Accounts and Import / Add another email account
Step #3 Choose the Name and enter your Outlook email address.
Step #4 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.
Step #5 Enter the confirmation code, which will be sent to your Outlook account.
Step #6 Go to Settings / Accounts and Import.
And choose your Outlook email as default.
Step #7 So now you can send Outlook emails from the Gmail interface and your emails will be tracked via Docsify.
Step #8 Go to Outlook / Settings / Accounts / Forwarding.
And choose your Gmail account.