Unfortunately, once an Campaign has been deployed, there is no way to change the content of the email in your Subscribers inbox. There are two exceptions:
- Tracked Links can be corrected
- Images can be changed
Tracked links can be changed using the Flex URLs feature.
Images can be "changed" by uploading another image of the same name to the location referenced in your Template.
For example, let's say you've uploaded an image to the Media Manager called "sale.png" referencing a 50% off sale. After the Campaign was sent, you realized that this weeks sale was only 25% off. Simply have your designer update the image to change the 50% to 25%, save the image using the same name, and upload it to the same location. The next time any Subscriber opens the email, it will show the corrected image.
In order to avoid issues like this in the future, it's a good idea to make sure your team has a checklist that is reviewed prior to each send.