There was plenty of documentation, and what I was trying to do was along the lines you mentioned. My problem was that if anything there were too many different moving parts in the software and too much documentation. Individually it was quite clear what each part was supposed to be doing. Collectively, it simply didn't work: messages weren't reliably sent or delivered, sometimes generating various kinds of logs or error messages, other times silently as far as I could tell. The hard part was trying to pin down which part of the system wasn't set up properly, and I simply didn't have and couldn't find the knowledge to solve that problem within a reasonable amount of time.
Given that fundamentally neither email protocols nor mail store structure on a typical Linux box are particularly complicated, and that all of the software I was using was well established and reputable, it was an exceptionally frustrating experience. Someone with more skill than me would surely have installed the relevant half dozen or so packages from the distro, edited a few configuration files to set up the remote mail server details and identify the local processes to each other, and had everything working within a few minutes. Unfortunately, without that knowledge the sheer number of options and possibilities was overwhelming and I never got that far. What I really needed was a one-page HOWTO for the most simple use case and a setting for each package that said "don't try to do anything clever or unusual", but what I had at the time was literally hundreds of screens' worth of detailed parameters and config file options, each written according to the conventions and assumptions of their own package.