I Have one requirement using Sharepoint 2010 Designer Workflows?

Hi All,

When user send email to document library with a specific word in Subject. The workflow will reply with a file attachment that has the same name from the library.

Example user1 send email to doclibrary with "Account names" in subject doclibrary replies to user1 with a file attachment "Account.xls"

How to do this workflow using SharePoint 2010 Designer.

Thanks in advance.