If you simply want to send a new email we'd advise creating it from scratch so that there is an audit of this on the patient's contacts, see: Sending a Patient an Email

If you need to resend emails that have already been sent (or attempted to send) from EXACT because they failed to send the first time (i.e bounced back as undelivered and it's now safe to send them again):

1. Go to File, Email then select the Sent tab
2. Highlight an email by left clicking or select multiple by holding CTRL whilst left clicking then delete the emails you have highlighted using the bin icon in the bottom right corner
3. Then go to the Deleted tab and highlight the same emails you just deleted.
4. Select the "Move" button at the bottom and then select the "Outbox"
5. Click OK to accept
6. The emails you moved back to the Outbox will now be resent to the same patients