Where drafts are saved
There is no auto-save. A campaign is saved as a draft only when you click the Save Draft button inside the campaign editor. Until you do that, your work exists only in the browser.
If you clicked Save Draft at least once, the campaign was written to the server with a status of Draft and you can return to it at any time.
How to find a saved draft
In the left navigation, go to Email Campaigns.
The campaigns list shows all campaigns for your organization. Look for the Status column and find entries labeled Draft.
Click the campaign name to reopen the editor and continue where you left off.
If the list is long, use the filter bar to narrow to Status = Draft.
What to do if you did not save
If you closed the tab or navigated away before clicking Save Draft, the unsaved work is gone. You will need to start a new campaign. Click Create on the Email Campaigns page to begin again.
Tips to avoid losing work
Click Save Draft early, as soon as you have given the campaign a name. You can come back and edit every field later.
Each time you make significant changes (updating the audience, editing the email body, changing the subject), click Save Draft again before navigating away.
A campaign stays editable as long as its status is Draft. Once it is scheduled or sent, the fields are locked.