We have need to create a custom Mail Transfer Agent that will allow us to direct emails through various other MTA's or delivery services based on sender email address. I know this can be done through Postfix, but if you have another preference, that's open for discussion.
... Recommend server specs for target email volume
2. Set up Postfix or other MTA software on one of our servers (we will provide ssh access); integrate Mandrill (we will provide certificate authentication) and demonstrate required functionality