If ever there was an "SMTP for Dummies" solution, it would have to be Microsoft's SMTP implementation for the Internet Information Server (IIS) of its flagship Windows server products. The product comes free with Windows Servers and just needs to be installed and configured, as it does not normally come pre-installed by default.
I recently migrated my servers to the "cloud" and was faced with the prospect of having to run my own SMTP service as the data center does not offer a centralized SMTP service. Linux is normally a much more robust solution, but my skills in setting up SMTP date back to more than a decade ago. I'm so out of touch already with going down that route so I considered the easier way out -- Microsoft IIS.
Installing the SMTP service only takes about a minute. One just has to follow these steps. Setting it up is also just a matter of pointing-and-clicking for the most part as described here. In no time at all, the SMTP service was up and running!