Need mail server designed to receive xml attachments and save them to sql database

Must have the following functionalities.
1) users (mailboxes) should be created, deleted or updated via webservice or by database queries.
2) xml attachments should be saved in binary.
3) other attachments should be discarded.
4) Email text should be saved in database.

This is the first part of a much larger project. The full projects includes the development or a web based ERP SaaS solution.

Please contact me if you need clarification on any.

I'm not sure about the price so I'm willing to listen to proposals