Selfhosted

The value in those products is that it takes much less management, brings much greater reliability, and support teams if you have issues. If your dinky NAS shits the bed, the company's data is gone, the company is kaput, you are all out of a job.

Of course there is a middle ground. I know there are plenty of open-source hosted products. They're still subscriptions, but that monthly expense probably comes out cheaper than the time and effort building and maintaining your custom systems.

If you still really want to host it yourself, make sure you run through your disaster and recovery scenarios. You will have to have a 3-2-1 backup system. And remember because shit will go wrong, two is one, and one is none. That includes you personally, in the event you get hit by a ~~bus~~ lottery.

I would recommend an actual Dell tower server with idrac for remote management, and with prosupport for when something blows up (sometimes literally, I had one PSU go bang on a server under my desk at one point). Fill it with enough disks for redundancy and data growth for the next few years, but leaving room for expansion. Put your favorite hypervisor on it, set up some vms or containers to run those services, test backups, and document everything so that a semi-trained monkey can follow it.

But don't host your own email. Getting each individual email server to not consider you spam is a Sisyphean task.