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