Using self hosted email service is a big mistake in 2026.
Experience shows that the walls will get taller and the moats will get deeper.
The solution is allow only communications that are demonstrably not spam and not unwanted.
There have been lots of proposals to this effect but maybe you have to put up two cents in a crypto wallet, which the other person can claim if the mail is unwanted. If someone takes your two cents, you remove them from your lists ASAP. The receiver doesn't benefit meaningfully from the 2c so they are unlikely to claim it. The sender is only damaged if a lot of different people claim the 2 cents. Maybe a few domains are default whitelisted even if they don't put up 2 cents, to protect against entities that are important but would be frequently spite-claimed (IRS, courts, and other similar). If you use a provider that doesn't whitelist, fine, but you're going to miss those emails.
Maybe the top 'spite claim' users are published and it becomes difficult to get people to agree to put up money to talk to you.
This reduces spam to the level of junk mail, which is still not totally trivial but is orders of magnitude more manageable.
Seems they are the disease not the cure
It seems insane that gmail doesnt provide a way to automatically send a mail (eg based on domain, keywords, etc) to spam. I know theres block sender but for example aliexpress uses a different name for every email so that's useless.
Lately I've also been getting a lot from compromised MS365 accounts.
What this is called is survivorship bias. The question I would ask is how much mail are you not seeing at all because it's dropped at the edge first thing because it's IP block listed?
Next, how much spam are you seeing from them because they and Google are the largest providers on Earth? Kind of like selecting a random person from the population in the US and going "look, it's a white guy". Yea, that's how statistics works.
Lastly, because the are good at blocking spam at the edge, then that's the last bastion of attack for spammers to put their efforts in if they want any return at all.
Self-hosting allows me to use a different receiving address for each entity I contact, so I know exactly who put me on spam lists and if it gets bad I can route that address to the garbage bin.
Anecdotes are not a great thing to run mail servers on, broad statistics are.
These entities communicate via plain old mail, that costs more than 2 cents already.
There is and it's the same as other protocols including proprietary ones - a sender address whitelist.
There's no proprietary protocol that solved spam either.
We have dozens of different ways to send E2EE messages to each other, with realtime publish-subscribe, and yet billions of dollars are spent trying to duct tape email. Who cares if Outlook/Gmail/Icloud use IMAP or Websocket? If the interface looks the same to the end user will they really care?
Experience shows that the walls will get taller and the moats will get deeper.
The people working on outlook.com are just talentless amateurs - the rest knows how to do it right. It's a shame it's so widely used.
Most of them wouldn't even care probably...
What about tencent.com, foxmail.com, or qq.com?
User signs up, uses @outlook. Your app declines it and explains that they block with no way to remedy, and explain they are a bad vendor.
Emails would be accepted by Outlook.com, but would never deliver. We had SPF/DKIM/DMARC and full reporting. They RBL'ed us with no remedy.
We told the customer to not use outlook.com BECAUSE we told them we could not guarantee any delivery of messages.
Means you're not using your email seriously. For example, to send CVs in response to job postings.
I send up to 20 email per day to people who have issues with their package build scripts, and I have no idea whether they ignore me because they stopped using the distro or because mail got dropped.
You should be able to see this on your DMARC dashboard
Fortunate for those running their own servers is that they actually still get all the cool emails from people not complying.
At the most you need to use an external service for delivery (usually because you have problems with MS) but you can still run your own server with no difficulties once you do that.
That said, DMARC is required by a lot of people now, so I do not think this particular issue is a problem.
I have been self hosting my my personal email (and for family). Few problems so far other than delivery to MS and I have recently moved a domain I use for work email over.
Oddly enough the MS problems come from hotmail, but not other services. If that is a problem, then pay a bit to have email delivered.