Since they are old, i would imagine the power efficiency isn’t the best on them for a 24/7 HA cluster at home. Unless you have an abundance of solar power or something. So I would use them as a test branch for whatever I want to do for self-hosting and learning

I would use them as learning platform for myself. Play with Active Directory DCs, replicataion, failover, recovery, networking etc. Just because more practice in that is what would be needed for advancement at work.

Others mentioned Kubernetes and Proxmox clustering. I could also use some sacrificial storage and compute to play around with those technologies so I could improve my self-hosted services.

Yeah, I tried tuta. I have (overall less but) the same issue with proton. I just want to use my own client apps of choice.

I have registered with mailbox.org and while the trial period is very limited, the web ui is minimalistic and basic looking. You could say outdated. I seriously consider paying for a “team” account for me and my wife. The price is unbeatable. Aside from the gui, the features I need are there.

I just need the Wife’s approval. She’d be migrating from yahoo of all places.

I can second most of the suggestions. I do not host an office suite (for now?) but I am syncing my keepass dbs over syncthing along with my notes and important documents. I think since 2016 or so. It works well.

Before I had a server I just synced them in a triangle between my phone, laptop and desktop. Most things had 3 copies this way. Any device could offload changes to another. Now I have a central node and the option to sync as before if the server is down. With Tailscale, I don’t need to be on the same wifi now eiter.

The keepassDX limitations are not a big deal if all you need is basic autofill.

Mail providers are hard to chose. I am leaving proton for the lack of easy smtp and their locked in nature. Get your oen domain and you will be able to switch more easily in the future.