Within Survey Settings/Publish Survey, there is the option to 'Display the 'Save Draft' and 'Load Draft' buttons:
If checked then the survey form will include 'Save Draft' and 'Load Draft' buttons at the top of each page (including the personal details page:
If the respondent completes part of the survey and then decides to 'Save Draft' to complete later they will be prompted to enter an email address and a password:
An email is sent to the email address supplied with a link to the survey. The respondent must click on the link to access the survey using the credentials defined and select 'Load Draft' to reload their previous responses. This is an example of the Save Draft notification email format:
Please Note: The Draft Survey Response email template is not configurable.