Login to your newsletter app
https://mail.musicprosite.com
Email: YOUR_SITEBUILDER_USERNAME@musicprosite.com
In the left hand menu, click on Campaigns > Autoresponders
Find the email you want to edit. Then scroll right
Click on Pause and wait for the screen to refresh
Now click on edit
Click on Template
Edit the email as you wish:
Scroll to the bottom and click on Save and next
In the next screen, click on Save and activate