On the Mail Streams tab, the Overview screen shows the email template being used for the mail stream as well as its status and change history. You can also add a description of the mail stream (e.g. its objectives and scope of use) and delete or deactivate it.
Making changes to the template
Once a template is associated with a mail stream, the mail stream takes a snapshot of the template and uses that. The mail stream refers to this as the Production template. You can continue to update the template without affecting any of the emails being sent. The modified template is referred to by the mail stream as the Staging template.
Click View Changes for a side-by-side comparision of the production and staging templates, as a straightforward code change:
And as HTML or Text version previews:
If you want future emails to be sent using the new content, click Apply Changes. This will update the production template and add a new entry to the change history, with whatever description you have added.