I'm thinking of doing something similar and hope to learn from your experience. I have two questions. (1) Was it easier to write your own MTA than to use the mi

I'm thinking of doing something similar and hope to learn from your experience. I have two questions. (1) Was it easier to write your own MTA than to use the milter interface to Postfix or other mature MTAs that support it? (2) How would you set up the MUA to use the right alias in the return address when users reply to a message instead of leaking their real email address? (e.g., Would you need another lookup table somewhere that maps (user,recipient) pairs to user aliases?)