Who has access to your email?
Tuta and Proton Mail encrypt your mailbox, and both say this leaves them no way to read your messages. Tuta encrypts subject lines too. Proton doesn't, and says that keeps its mail compatible with other providers.
Between two Tuta users, or two Proton users, email is end-to-end encrypted without any setup: only the sender and the recipient read it. To people on Gmail or Outlook, both send a password-protected message that opens in the browser.
mailbox and Infomaniak work differently. At mailbox, you set up PGP encryption in the webmail yourself. Infomaniak encrypts an email when you click the lock icon, but keeps the keys in its own data centres and unlocks them when you log in.
Where is the company, and where is your mail?
Two of the four services here have their head office in an EU member state: Tuta in Hanover and mailbox in Berlin. Both say they keep your mail on servers in Germany.
Proton Mail and Infomaniak are Swiss companies. Infomaniak says your mail stays in its own data centres in Switzerland. Proton says its servers are in Switzerland, Germany and Norway. Switzerland is not in the EU, and Swiss court orders have made Proton hand over metadata such as IP addresses.
How much do you get for free?
Gmail gives you 15 GB free, shared with Google Drive and Google Photos. Only Infomaniak offers more: its free plan comes with an @ik.me address and 20 GB for email. Tuta's free plan has 1 GB. Proton Mail starts at 500 MB, grows to 1 GB after a few setup steps, and lets you send 150 emails a day. mailbox has no free plan, only a 30-day trial.
On a yearly plan, mailbox costs €1 a month for 2 GB. Tuta asks €3 a month for 20 GB, and Proton €3.99 for 15 GB. Infomaniak's my kSuite+ costs €19 a year, with no limit on email storage.
Do you want your own domain?
Tuta and mailbox let you use your own domain from €3 a month, Proton from €3.99. Tuta's plan covers up to three domains. Infomaniak's Starter plan gives you one free address, and you pay only for the domain. Infomaniak says some domains cost less than €5 a year.
Do you want to keep your email app?
If you read mail in Outlook, Apple Mail or Thunderbird, check this before you sign up. mailbox works over IMAP and POP3 on every plan. Infomaniak publishes IMAP setup guides for Thunderbird and Outlook. Proton lists IMAP access through its Bridge app on paid plans such as Mail Plus. Tuta says its encryption rules out IMAP, so you use Tuta's own apps.
Moving your old mail works differently too. Proton's Easy Switch copies messages, contacts and calendars from your Google account. Tuta imports EML and MBOX files in its desktop app, and lists that only on the €8 Legend plan.