Do you want to be able to schedule emails with gmail? I mean you want to write an email today and set it to be sent later for perfect timing.
We live in different time zones and some times, there is need to make sure your message gets to your recipient just at the moment they are available to read it.
If you are doing some email marketing for your business, you must be using an email marketing platform like MailerLite that allows you to create and schedule campaigns.
Now, this is something that lacks in almost all of the personal and business email services. Most of these would only provide facilities for Vacation Auto Replies or Out of Office messages.