Not sure, why you want to host email yourself. If it is just for privacy reasons, you could also have a look into posteo.de (I am customer for years, no ads, nearly zero spam, you can even pay with cash if your like) or mailbox.org. German providers and especially posteo is really tracking a minimum amount of data, just as much as they are required by law.

I self-host incoming mail and send outgoing mail using Mailjet's free plan to ensure deliverability. I've used them for several years and found them very reliable. Occasionally our outgoing mail is routed to spam despite having our DKIM and SPF records set per Mailjet's instructions. I'm not sure anyone else would be consistently better based on emailtooltester.com's annual deliverability reports. Their maximum attachment size is 15 MB, but they don't recommend anything over 5 MB, as some providers block anything larger than that (which I've found to be true).

I self host my own mail, SMTP in and out. But I've also had this vps in the US from a small local hosting provider for a decade. Unfortunately vps providers can be a crap shoot if you're looking for a new one. My back up plan is this one goes south is to just use a cloud provider's SMTP relay service (eg aws) because their prices for that sort of thing are extremely reasonable for small volume.

I use mailjet with tls on port 465 for all self hosted

it provides me with end-to-end security and ensures that emails arrive at the correct destination, it's much less burdensome to manage

Is free over 6000 mails / month (200 days)

I use smtp2go service. Free tier more than enough for personal mail!

I just host from my garage using courier http://www.courier-mta.org/

Maybe it's hard to do in other countries but in Australia I've done this since about 2008 and moved around a lot and used different static ips.

Mail isn't hard. Just don't set up a shit server