You can create a new email message from a previously sent message. This creates a new email and a new sent message report. This is possible for legacy emails and those created in the new Email Composer. There are two ways to do this: From the Email Composer, or from your Sent Messages.
If you need to re-send a Sent Message because it has failed, see our related guide: Managing Failed Email Messages.
From the Email Composer
Click Outbound > New Message > select Sent Message:
From Sent Messages
Go to Outbound > Sent Messages hover over a previously sent email message, and click New to begin using the email composer.