If you are okay with Docker, I would recommend checking out mailu.io (no affiliation, just a satisfied user). It provides a really powerful and flexible setup

If you are okay with Docker, I would recommend checking out mailu.io (no affiliation, just a satisfied user). It provides a really powerful and flexible setup without spending your entire life wrestling with configs (plus it is open source!). In my experience, though, unless you are going to be running a pretty high-volume setup (where you can quickly build a good reputation for your SMTP address), you will probably still need to route your outgoing email through an external SMTP really to make sure it does not get flagged as spam. (I use Amazon SES which is close to free for low monthly volumes...)