Email Archive Simulation Setup

I would like an email account setup with backdated emails. I would like it to appear that emails were sent and received on earlier dates. I will create the content for the emails both sent and received. I just want the ability to edit the dates. If possible, I would also like the ability to import emails from my Gmail account to help with authenticity. The email account can be through an existing provider. But I need the emails to show as if they were sent/received on an earlier dates. Please let me know if you can assist or if you know someone that can.