Related Questions:
Why can't I find old emails?
Where did my guests' email history go?
How far out can I Schedule an Email?
Environment:
Event Temple Web App
Answer:
Regardless of which email provider you integrate with, emails are stored in Event Temple for one year. After this, they will be permanently removed from the system.
This includes sent/received items as well as any scheduled emails.
Please note, this does not affect email communication in your email provider.