How to create an inbound email service in Salesforce?

To Create Inbound Email Service: go to Setup → Build → Develop → Email Services.
Before creating Email Services, Create Apex classes that implement the Messaging.InboundEmailhandler interface. Using the handleInboundEmail method in that class, you can access an InboundEmail object to retrieve the contents, headers, and attachments of inbound email messages, as well as perform many functions.
After Creating Apex Classes based on the requirement, Create an Email Service:
1. Click on New Email Service, Enter Email Service name
2. Choose the appropriate class which you created earlier. Choose the type of attachments you want to accept.
3. Click on the Advanced Email Security settings checkbox.
4. Choose whether to convert text attachments to binary attachments and active checkbox.
5. Configure Failure response settings and click on save.