On-Demand Email-to-Case:

On-Demand Email-to-Case uses Apex email services to convert email to cases.

Steps for implementing On-Demand Email-to-Case:

1. Define email addresses on your email system for case submissions.
2. Create email routing addresses that include the addresses defined for cases.
3. Configure your email system to forward case submissions to the Email Services Address provided to you by Salesforce.
4. Enable On-Demand Email-to-Case.

Email-to-Case:

Email-to-Case requires downloading the Email-to-Case agent.

Steps for implementing Email-to-Case:

1. Download the Email-to-Case agent from the Apex Developer Network(http://wiki.apexdevnet.com/page/Members:Email_To_Case)
2. Install the agent behind your network firewall.
3. Configure email routing addresses.
4. Enable Email-to-Case.