Customize URL parameters (UTM/Google Analytics)
Access this feature int the Email section of your Digest editor, under "Advanced Settings".
Under "Options" look for UTM Parameters. Turn the feature on, specify your domain name, and adjust the parameters to best fit your needs. We pre-populate the parameters with default value but feel free to adapt it to your needs.

Default value is set to: utm_source=Marketo&utm_medium=Email&utm_campaign={{digest_name}}-{{digest_send_date}} where
{{digest_name}} = name of your Digest.
{{digest_send_date}} = Digest send date.