The new mail server is almost finished.
Thanks to Lyssa and a quick run to Micro Center on Monday night, I had enough parts to put together a new mail server who seems to want to be named Akara. I'm not sure if Akara is male or female, but Akara is busily processing the backload of SMTP attempts that have piled up since Monday. I'm going to let her burn in overnight and then tomorrow I'll connect the drive that contains the original mailstore and start reconstructing accounts.