You can send an email at a later date using Gmail. And no you do not require any third-party apps or anything, Gmail provides these options to all its users and it’s super easy to do.

Scheduling email on Gmail can be really helpful – maybe for a birthday card email, or if you just want to bluff that you worked till late, etc ;). Anyway, to schedule an email on Gmail simply compose your email and on SEND you can click on the arrow next to it. This option will provide you to add a date and time to send the email.

Hope this helps.