Even 10 euro a month per user is nothing - their salary + insurance + taxes is probably 3-4 thousand euro at least, these 10 euro are a statistical error.

We use Office365, because we need Office anyway. We initially used a hosting provider email server, but it's not trivial to get the email DNS configuration right, and you risk going in spam. Even after we got our configuration right, we still had occasional "spam" issues.

Set the spf fields in DNS and you should be fine. It's not really that hard unless you do send out spammy mails.

How about Mailbox? https://mailbox.org/en/ (they support calendar sync)

or Zoho https://www.zoho.com/

It's hard to run a service below 3 Euro/month with good (human) support, those who do often charge annual. We use https://runbox.com/price-plans/ and are very happy. There was a discount for pre-paying two years and in our monthly cost spreadsheet with 30+ SaaS it's the service costing us the least.

There's several previous 'alternatives to gmail' discussions, e.g. https://news.ycombinator.com/item?id=17448108

If your own time is worth very little I suggest self hosting. It takes a few hours to setup.

Plus a few hours every week to chase down reports of emails not being delivered, spam, etc.

As someone with many servers and a previous career managing an email service for a university, I would never run my email through anything except G Suite or Office 365. The benefits of those services being "too big to block" is immeasurable.

What's nice about GSuite is contacts and calendar syncing on Android and iPhone.

Do realize that Android only supports GSuite. In other words, by default it doesn't support CalDAV and CardDAV. There are apps for that, but I found those to be a hassle.

I recently setup tutanota for my startups email needs. It's terrific. No frills, just works, secure and encrypted email. Can't be happier.

Edit: obligatory link tutanota.com

Plus one for tutanota. I've been using tutanota for years and love it. And the recent calendar feature is great.

Pretty happy so far with Migadu.

Agreed! Migadu is great considering they essentially give you a single mailbox for free and the upgrades aren't per user. The different tiers just have sending limits with the top tier being basically unlimited (at their discretion - they're just worried about spam, rightfully so).

https://www.migadu.com/en/pricing.html

Yes Migadu works well. Been using it more than 9 months now with only one minor problem, which was quickly sorted

One more happy user of migadu. Painless. Unlimited mailboxes. Only restriction is on the number of emails you send