I really want to try this, but I'm afraid my DNS will be blacklisted if I do. Can someone guide me and others, if this is the case? E-Mail is the most complex of everything I know in sysadmin/DNS/Server stuff.
My current provider since almost two decades without any issues, except speed and storage limitations is all-inkl.com, but I really just use it for email and nothing else, therefore most likely overpriced at ~6€/month.
I would love to switch to some VPS/root or anything where I can SSH and install, compile my own services, but something where security is high and support is 24/7 available.
> therefore most likely overpriced at ~6€/month
> something where security is high and support is 24/7 available
You are not going to get great 24/7 support inside anything like €6/month (though many may promise it!), so that service may not be as overpriced as you think.
Another thing to consider is that many VPS providers have “dirty” IP ranges so you will have trouble with getting your mail delivered. A common solution to this is to use a mail delivery service (like mailgun, mxroute, and many others) so your mail comes from a managed “clean” source and has less chance of summarily being declared spam just from the source address alone (these services also reduce the need to think about spf/dkim/etc and keep an eye out on changes that may happen in that realm). Essentially by self-hosting a service like this, you are taking back the admin of managing all that so you have to ask yourself if it is worth saving a few € per month, and consider what you might lose if something goes wrong and all your mail starts bouncing.
> switch to some VPS/root or anything where I can SSH and install, compile my own services
Be wary of most really inexpensive options here. In most cases you will experience performance degradation (at random times, or just almost always) and other issues due to noisy neighbours on oversold infrastructure.
> I really want to try this, but I'm afraid my DNS will be blacklisted if I do.
The best (but unfortunately time-consuming) way to get comfortable with this is probably to register a sacrificial domain and set it all up for that domain on hosts not associated with your domains that normally send mail. Play with it, break it, fix it, break it again, etc., until you feel confident you aren't going to screw yourself by trusting your own admin of all this on a domain that actually matters.
A VPS will not be cheaper - but you may get more for your money (more storage, unlimited accounts).
For something simple try https://mailinabox.email/
> would love to switch to some VPS/root or anything where I can SSH and install, compile my own services, but something where security is high and support is 24/7 available.
Those sound like expensive requirements to me. You want managed self hosted email? Some else providing support will be expensive.
Two things to unpack here:
1) Posthorn doesn't host email - no inbox, no IMAP so it doesn't replace what it sounds like all-inkl is doing for you. All it does is take the outgoing messages from any of your hosted/local apps and take care of the plumbing of handing them off to a transactional provider (like Resend or Postmark). Those servers are the ones sending the mail, using their IPs and their sending reputation. Any blacklist concern is really tied to your sending domain and not a new risk from Posthorn. Just the same setup you'd do if you were calling something like Resend directly. If you're following their guidelines, you'll be fine.
2) On the VPS side, if your goal is to be able to ssh in, install some stuff and run your own services, something like Hetzner is a well regarded EU centric option with solid technical support baked in. Security is mostly on you and down to what you install and how you configure it. That can be a huge learning curve and a whole other kettle of fish, definitely not without risk.