I am writing an application which will parse MTA responses and update a database indicating if the message was successfully delivered (dns: 200), or an error occurred (dsn: 511). As I am not a systems guru I decided to ask here, after some toying around to see which approach would be best to solve my problem.
I followed this guide, first, and which I had the most success with, as I was able to parse the message via my script. However the content was the message before it was sent to the remote mail server. So then I read this post; which explains how to use transport_maps. And as if there weren't enough options, there was this post about how to use an alias, instead.
Which of these solutions would be best? Again, I would like to track ALL responses, not just bounce responses.