Why can an encrypted mailbox not also work in Outlook or Apple Mail?
Because IMAP requires the server to hand your mail to a client, and zero-access encryption is the deliberate removal of the server's ability to do that. Proton Mail encrypts incoming mail with your public key the moment it arrives, so the contents exist on Proton's servers only in a form Proton cannot read. Tuta does the same, and encrypts subject lines and the calendar as well.
The consequence is that neither supports IMAP, POP3 or SMTP natively. Proton offers Proton Mail Bridge, a local application that decrypts on your machine and speaks IMAP to a desktop client, which restores compatibility on a computer but not on a phone. Tuta does not support standard protocols at all: its own web, desktop and mobile apps are the only way in.
Everything else in this category chose the other side. Posteo, Mailbox.org, StartMail, Mailfence, Runbox and Kolab Now all speak IMAP and SMTP, work with any client, and offer PGP as an option layered on top. That is a genuinely different threat model: the provider holds mail it could be compelled to produce, and PGP protects only the messages you explicitly encrypt.
Neither choice is wrong. The question is whether you need mathematical certainty that the provider cannot read your mail, or whether a European provider under European law with the client of your choice is the better trade.
What does Swiss jurisdiction actually buy compared with German or Dutch?
Switzerland sits outside the EU and outside the Five, Nine and Fourteen Eyes intelligence-sharing arrangements, and the Federal Act on Data Protection requires a Swiss court order for any access request. Proton Mail and Kolab Now both operate under it. Since Switzerland holds an adequacy decision from the European Commission, an EU customer can use them without standard contractual clauses.
Germany is the counterweight, and the argument for it is not weaker. German data protection law is among the strictest in the world, shaped by the country's own history with state surveillance, and Tuta has gone further than compliance by challenging German surveillance legislation in court. Tuta, Posteo and Mailbox.org are all German and all host in Germany, which means intra-EEA processing rather than an adequacy decision.
The distinction matters most for organisations. A public body or a regulated company frequently has procurement rules that treat intra-EEA processing differently from adequacy, because an adequacy decision is a political instrument subject to review while EU establishment is not. For an individual, the difference is largely theoretical and the architecture matters more.
How do you actually leave Gmail without losing anything?
The mail itself is the easy part. Proton Mail ships an import tool that pulls messages, folders and labels straight from Gmail, and Runbox and Kolab Now both provide migration tooling. Most providers here accept a standard IMAP migration, which moves years of archive without manual work.
The hard part is that a Gmail address is an identity. It is the recovery address on dozens of accounts, the login for services you have forgotten, and the address printed on things you cannot recall. The workable sequence is to forward Gmail to the new mailbox, then move the important accounts over a few at a time as mail arrives for them, and only close Gmail after a quiet year.
Aliases decide how painless that is. StartMail offers unlimited aliases, so every service gets its own address and the one that starts receiving spam can simply be deleted. Runbox includes 100 aliases and Mailfence 10 on the entry plan. Posteo offers none in the sense that matters, because Posteo does not support custom domains at all.
The strongest move is a custom domain. With your own domain the provider becomes replaceable: switching later is a DNS change rather than another migration. Every provider here except Posteo supports it.
When is a mailbox not enough, and you need a Workspace replacement?
When calendar and files have to be shared rather than merely present. A personal mailbox with a calendar is a Gmail replacement. A team needs shared calendars, shared contacts, shared documents and somewhere to hold a meeting.
Kolab Now is built for exactly that: email, calendar, contacts, tasks, notes, files and video conferencing on open-source Kolab Groupware, with ActiveSync for mobile. Mailbox.org covers the same ground with an office suite, cloud storage and video conferencing, though the video conferencing sits on the highest tier. Proton's ecosystem — Mail, Calendar, Drive and VPN — approaches it from the privacy side and is stronger for individuals than for shared team workflows.
The honest limitation is scale. None of these matches Google Workspace on storage or on the depth of real-time collaborative editing, and an organisation deeply wired into Google Docs will feel the transition. What it gains is that the provider cannot read the documents and cannot be compelled by a foreign government to produce them.
What does a private mailbox cost, and why is free suspicious here?
Email has an unavoidable cost: storage, spam filtering, deliverability work and abuse handling. A provider that charges nothing has to recover that somewhere, and in the mainstream market it is recovered by processing the contents. That is the trade this entire category exists to refuse.
The prices are modest. Posteo is €1 per month flat with no tiers to reason about. Mailfence starts around €2.50, Tuta around €3, Proton Mail around €4.99, StartMail at €5 billed annually, Kolab Now at CHF 4.41, and Runbox from €19.95 per year. Mailbox.org starts around €1 for Light and reaches €9 for Business.
Free tiers here are deliberately small rather than ad-funded: Proton Mail gives 500MB, Tuta 1GB, Mailfence 500MB. They exist to let you test the service, not to be a permanent home. StartMail has no free tier at all and says so plainly — every user is a paying customer, which aligns the company with its users rather than with an advertiser.
The cost that is easy to miss is storage growth. Several of these providers are modest on storage by Gmail standards, and a decade of attachments does not fit in 1GB. Check the archive size before committing, not after the migration.
