What is the best Email Service for ERPNext?

I want to implement the email service for the ERPNext. However, I was confused about which email service should use. Like I know how to create a service for sending mail using SMTP. I need suggestions from the cost perspective.

Reference Documents

I use Google Workspace for bulk mailing and haven’t had an issue so far.

Are you sing the Email Account in erpnext like configure a mail and bulk and signle message through code. using frappe.send_mail()