I've been running Postfix servers for four years, and one whose reliability is important to me for a year and a half. While it's working well enough, with zero unplanned downtime in that time, I find Postfix configuration to be complete voodoo. In particular:
- Rewriting rules - I have no feel for what Postfix is up to. I administered an Exim mail server some years back, whose approach to rewriting made sense to me.
- Security - I have internalised no threat model for Postfix. Securing Postfix to me means avoiding changes to config files that don't keep to the letter of advice from a trusted source, and keeping Postfix up-to-date.
- Encryption - I'd like to know the role that things like SASL, TLS, &c, can play in the life of a Postfix server.
What should I read to get a clue about these things? I think I'd prefer an article or report to a howto or book.