I use mailbox.org but if you have your heart set on self hosting id say stalwart is a good selfhostable email service

Instead of hosting your own mail server, use a service like SimpleLogin. It allows you to configure custom domains on the paid plan and it simply redirect any email sent to an email alias to your actual inbox. So you never share your actual email address. Secondly, if tomorrow you change email providers, all you have to do is change the destination behind those aliases for the custom domains. It also does catch-all aliases so you can make them up on the fly.

I moved away for self hosting email, but my advice would be to look at anti spam providers. Most can act as both an incoming and outgoing filter for your emails, and will hold on to email if your mailbox host is down. It also means for outgoing you don’t need to warm up an IP to have your messages accepted.

Of course you still need to setup SPF/dmarc/etc but it takes out some of the fuzzier parts of email deliverablity…

I own a business. We hit 9 years in September. When we started we did O365. At that time, a business as small as us had to go with a Microsoft “partner” because MS wasn’t going to deal with a business as small as us. We were immediately “man in the middle” hacked. We’d been in business 3 months and someone was grabbing our incoming emails and replying as if they were us. We had no idea. They changed payment terms and re-routed our checks as direct payments to some digital accounts in Miami (USA). I have no doubt that it was our Microsoft “partner” that set us up with O365 and Lync (this was a long time ago). When we pressed Microsoft about it they became totally unresponsive or nasty. We lost about $25,000 dollars right at the very beginning of our business. It was a very dark time for me. But, honestly, that was the best $25K I ever spent. Talk about “attack Surface”.!!! Now I do Fastmail, Nextcloud a nd other self hosted services. I am absolutely convinced that losing $25k was an absurd bargain. People on O365/ SharePoint/Teams get hacked every fucking day. But they don’t tell you about it.

1. Get cheap Hetzner VPS with redundant volume.
2. Get a domain name.
3. Run Stalwart for you mail server.
4. Run Bulwark for your inbox web app.
5. Run Kanidm for an identity provider.
6. Configure these DNS records: MX, SPF, DKIM and DMARC

There are more details, but those are the basics.

Mail is something I don’t want to touch. I use mailbox which is hosted in germany for some years now. For calendar & contacts I use the built-in Nextcloud apps, they also work pretty well

Edit: I self-host Nextcloud, so contacts & calender are on my private server

Docker mail server dms on hetzner , if you set your dns for multiple mx you can have a fallback at home or another dms in a different data center and replicate it with dovecot sync

I self-host it with https://gitlab.com/simple-nixos-mailserver/nixos-mailserver.

• I had to set it up with all these SPF and DKIM and DMARC stuff. Wasn’t too hard, just follow the guide. Test with GMail - the message details view says exactly what you have, what you haven’t, and what’s wrong.
• Every now and then I have to jump through some hoops to get my IP allowlisted in some weird provider or antispam system.

Email is a very old protocol, it originates from the time when computers were connected only occasionally. It is very much possible to come an agreement to power up the antennas at something o’clock every day to exchange emails, and the rest of the time they just sit in the queue.

Practically speaking, if your home lab is down for something like 12h, it should not impact email delivery much at all - the sending servers would just keep retrying. Usually for 48h. From https://www.rfc-editor.org/rfc/rfc5321#section-4.5.4.1

mail that cannot be transmitted immediately MUST be queued and periodically retried by the sender.

The sender MUST delay retrying a particular destination after one attempt has failed.

Retries continue until the message is transmitted or the sender gives up; the give-up time generally needs to be at least 4-5 days.

Microsoft documents this: https://learn.microsoft.com/en-us/defender-office-365/mail-flow-about#mail-flow-delivery-faq

Deferred messages remain in our queues for one day.

I guess technically they’re RFC-compliant, but 1 day is not as much as I’d like…

I’ve self-hosted email for over 20 years but I’m now moving to Fastmail for two reasons: (1) succession, I’m the only one in my house that understands how it works, and (2) email is never fully under your control and the large providers may decide to filter/drop email from your domain. But this is self-hosted, and I did enjoy my years doing it, so go for it if you want. I had good luck with OpenBSD/OpenSMTPD/Dovecot stack. Good luck!

Edit: I forgot to mention you can do a hybrid approach; handle receiving yourself and use a service like smtp2go.com to do delivery.

Mail is a piece of software I won’t bother self-hosting. I already tried, put in it a lot of time, trying to get my IP address considered safe because it was banned 15 years before I had it, to only have a third of my mail sent successfully received. It is not worth the effort and I switched to proton and recently to infomaniak.

Self-hosting email is like making your own butter.

It’s possible, but most people don’t want to take it on themselves.

Calendar and contacts I’d argue are good candidates to self host. If a config is off and you can’t access them for a day or two, does it matter?

But if email is down, you risk missing something important. If you have a trust issue and everything you send is getting flagged as spam? Hard and slow to fix.

If the problem you’re trying to solve is Flaky and Unethical Big Tech, I would look at finding another, smaller provider and paying for it. Rolling it yourself is a great way to learn entirely too much about mail servers and spending way too much of your free time on it.

One thing you should know, the SMTP protocol is designed to work with intermittent network connections like modem, each email has several days of grace period, with many retries, so you don’t need 99.999% uptime.

Just a mailbox at IONOS for 1x Business plan and 25 “free” (2gb) mailbox.
Costs me 7€ per month. And so far almost zero downtime.

I’m going back to my KISS mindset.

I got the Mozilla ThunderMail invite and using ThinderBird for the client. It’s all basic, direct and just works.

Agree with most folks here, mail is too hard to self host because of the control larger providers hold around acceptance rules. I use zoho for my email, been pretty solid so far though I’m sure there are others. I use nextcloud for contacts, tried using nextcloud for calendar but had trouble getting it to send invites to people so I just use zoho for calendar as well now.

Off site fallback I sync email, calendar and contacts to multiple machines but I also use back blaze as an off site cloud backup. One day I’ll get around to syncing the emails to my home server and also backing those up to backblaze.

This is all for personal use though, if I was doing anything enterprise or mission critical I’d just pay another provider to do it who isn’t a vibe coded nonsense factory.