Any way to add mailbox info for email in .net core?

I am learning asp.net core and following this doc - https://docs.microsoft.com/en-us/aspnet/core/security/authentication/accconfirm

I see the doc explains how to user email confirmation option using SendGrid account. 

But what if someone do not want to user Sendgrid?

How SMTP settings used to be in webconfig in asp.net mvc websites, there is no way to do that in asp.net core?

How can I user a normal mailbox for emails purpose? so that all email functions use that mailbox credentials?

Plz help?