Yes, we do support email-based approvals.
When your workflow moves through different process steps, you have the option to trigger email
to the both the submitter and reviewer.
In the 'Create Flow' screen of designing your workflow, you have the option to select the check box to send email for approval.
This is shown in the below screen shot.
When the conditions are met in the workflow, email will be triggered to the concerned people.
The reviewer can reply the email with the keyword like 'Approved', 'Completed' etc and send the email.
This will cause the process to be approved.
The key word required to be used in the approval email will be specified in the email trigger received from the 'cflow emailer'.
One such sample email screen shot is shown here.
