We have a project specific folder in the SharePoint document library and incoming email is enabled. We expects that whenever Email is send, SharePoint should store the attachment into the project specific folder.
Is it doable ? how?
If you've enabled Incoming Email in Central Administration, assign the Document Library an email address in Library Settings -> Incoming Email (this is where you can also configure how attachments are handled and if original emails are saved). Then let your user community know to send project information to that email address.
If you have not enabled Incoming Email, here are some links which cover the process (which is fairly extensive depending on your mail server and how SharePoint is configured).
It involves setting up an appropriate MX record/domain, routing mail to the SharePoint server via MX/DNS, enabling the Foundation Incoming E-Mail service instance on the target SharePoint server, and finally configuring Incoming Email in System Settings -> Configuring incoming e-mail settings.