TLDR: "How do you self-host email" – that's the thing, I don't. I don't host email sending and receiving myself, just the archive.

Here's a starting point for EU-based providers. If you give more details about your needs (how many mailboxes etc.) we can advise or recommend.

My main criteria is access through regular IMAP/SMTP without any made-up hurdles (cough Proton "email bridge").

Based on your need for email + calendar + contacts I'd say mailbox.org is a likely candidate. Please note that you pay separately for each mailbox (distinct login) but you can establish a "family" relation between accounts for sharing data.

What I do personally:

• Self-host a CalDAV/CardDAV server (Radicale) for calendar/contacts.
• Use a regular email provider (Migadu) with my own custom domains.
• I access the live mailboxes via IMAP from various email clients (desktop, phone etc.)
• Same for sending, use the provider's SMTP.
• I use mbsync aka isync to fetch a copy of all email to my server and delete messages older than 30 days from the live mailboxes.
• I self-host a private IMAP server and webmail mainly for browsing and searching this mail archive. I don't send from this webmail (although I could connect it to the live SMTP if I ever wanted).

If I ever need to switch providers I can do it as fast as I can sign up / pay with someone else and all it takes is updating the IMAP/SMTP server address on the various clients, and the DNS records for my email domains. Nothing else changes about the setup.

Why Migadu: they have a pricing model where you pay for storage and emails sent/received but can otherwise have unlimited domains, aliases, mailboxes, logins etc. It can become price-efficient very rapidly if you use it for 2+ people and/or have multiple email domains because this is exactly where regular providers corner you – they tax per mailbox, per domain, if you want more than a handful of aliases etc.