Custom MAPI DLL

I'm currently using a 32 bit 3rd-party software (no source code) that uses Extended MAPI to send email by inserting into Outlook PST*, presumably via [login to view URL] (coder to investigate and confirm prior to confirmation of job). However, since Outlook 2010 is no longer for sale, and Outlook 2013 doesn't work on Windows XP, I'm searching for coder to create a Custom DLL (in place of [login to view URL]) that can capture and response to MAPI calls from the 3rd-party software and then send the email data to a localhost SMTP Server. See attachment for complete description and diagrams. Thanks.