Mixmax enables you to schedule an email to be sent later.
How to schedule an email to Send Later
In the bottom bar of the compose window, click Send Later. You can choose from a preset time (e.g., In 1 hour) or enter a specific time. Send Later has natural language processing, so you can type almost anything in that box.
You can customize the options you see in your Send Later menu. Go to the Reminders & Send Later area in your Settings. Customize your preset times for when your emails will be sent.
Where to find your scheduled emails
To see and edit the emails you've scheduled to send later, hover over the M in the top right corner of Gmail and click Outbox (shown below), or you can go directly to the Outbox in your Mixmax dashboard.
In the Outbox, click Send Laters in the left column to see only your scheduled emails.
Click the checkbox to the left of a scheduled email, and Mixmax will give you the option to Reschedule or Stop the email, which moves it to your Drafts folder.