Proton Mail vs Fastmail 2026: Privacy or Productivity?

I have used both of these as my main inbox. Proton Mail came first, when I left Gmail, and Fastmail came after that. So this isn’t a spec sheet. It’s what living with each one was actually like, where they really differ, and who I think should pick which.

If you need your email company to be unable to read your mail, Proton is the one. If you don’t, I found Fastmail the better inbox to use every day. The rest of this post is the detail behind that, so use the contents to jump to whatever matters most to you. Plan details, domain limits, data locations and transparency figures were checked against both providers’ own pages on 8 October 2026.

Who should pick which

If you only have a minute, this is the quick version.

How I ended up using both

I used Gmail for my personal email for years. The more I wrote about email and privacy, the less comfortable I was with my mail sitting with a company that makes its money from advertising. Proton was the obvious place to go. It’s paid for by its subscribers, it’s based in Switzerland and it’s built so that Proton itself can’t read the mail stored in your account. I wrote about that move in Gmail vs Proton Mail.

I didn’t leave Proton because of privacy. I left because of the small things I ran into every day, which I go into below, and in the end my renewal date came round and I had to decide whether to pay for another year. I moved my main inbox to Fastmail and kept a Proton address for the mail that needs extra privacy. The full story, and the exact steps I followed, are in why I switched from Proton Mail to Fastmail.

For completeness, my mail now runs through Google Workspace, for work reasons that have nothing to do with either of these. I explain that in my Fastmail review.

Proton Mail and Fastmail side by side

The two of them set out to solve different problems. Proton is built to keep your mail unreadable to the people who run it. Fastmail is built to make email fast and dependable.

The big difference is who can read your mail

Most email services can read the mail stored in your inbox. That’s how they make search instant and build extra features on top. Fastmail works that way. Your mail is encrypted on its servers, but Fastmail holds the keys.

Proton works the other way round. Your stored mail is locked with keys Proton doesn’t hold, so if it were ordered to hand over your inbox, it could hand over the encrypted data but not readable messages. I go into more detail in what zero access encryption really means.

How well a message is protected on Proton depends on who you’re emailing.

Is Fastmail right not to offer end to end encryption?

Fastmail is quite open about this. It doesn’t offer end to end encryption in its own apps, because it says it doesn’t believe it “provides a meaningful increase in security for most users” and the trade offs are significant. It supports PGP and S/MIME through many third party apps, and its security page points anyone who really needs end to end encryption towards Signal rather than email.

Is that honest engineering or a convenient excuse? I think it’s mostly honest, and here is why, with one point of my own.

1. You still have to trust the webmail

When you use encrypted webmail, your browser downloads the code that does the decrypting from the provider every time you open the page. So you still have to trust the provider not to send you altered code. If a provider were compromised, or forced by a court, it could quietly swap in a version that captures your password or messages before they are encrypted. Software installed on your own device, such as PGP in Thunderbird, avoids this because its code is checked separately from the provider’s servers.

2. Email was never designed to be private (my own point)

Email dates from the 1970s and was never built with privacy in mind. PGP can protect the body of a message and its attachments, but not the sender, the recipient, the servers it passed through or the times, because servers need those to deliver it. And if you email someone on Gmail or an unencrypted company server, the protection ends the moment the message lands there.

3. It makes everyday email harder

Because Fastmail’s servers can read your mail, they can index a very large archive and give you results almost instantly. Proton’s design pushes that work onto your own device, which uses processing power, storage and battery. If you lose your password and recovery details on a true zero knowledge service, your old mail is gone for good. Normal IMAP and SMTP get harder too.

So I think Fastmail’s reasoning holds up for most people, especially if what you want is to get away from adverts and profiling. Where it undersells things is the bigger, quieter risk. Zero access encryption does protect you from a breach of the provider’s servers or a bulk data leak in a way Fastmail’s setup can’t.

How Proton answers that

Where Fastmail sees friction, Proton sees an engineering problem to solve, and it has done a lot of work on it.

• Zero access encryption for stored mail. Even mail arriving in plain text from Gmail is locked with your key as soon as it reaches your inbox. After that, Proton’s staff can’t read the stored messages.
• Encrypted search on your device. Proton downloads and decrypts your messages on your own device to build an encrypted index. It takes time and storage to set up, but you get full text search without Proton seeing your mail.
• Proton Bridge. To use Apple Mail, Outlook or Thunderbird, a small app on your computer does the decrypting and passes mail to your mail app as normal IMAP. Bridge is only on paid plans.

For the right person that is exactly what’s needed, and it’s why Proton is the default choice for whistleblowers, journalists and activists.

But it has limits. It doesn’t hide who you email or when, and it doesn’t hide who you are from Proton itself. I covered that in Proton Mail protects your messages, not your identity, and I go into who really benefits in who zero access email is really for.

I’m also not convinced Bridge is a good everyday answer. It works, but needing an extra app installed just to make my email work doesn’t sit well with me. I understand the reasoning. I just prefer how Posteo handles it, where zero access is an option you switch on and it spells out clearly what you give up when you do.

What using them every day was like

Because Proton can’t see your mail, it can’t do as much to help you with it, and I noticed that every day.

Search. Proton has to search on your own device, and with a large archive I noticed the wait every time. On Fastmail I searched tens of thousands of messages and had results in well under a second. I stopped filing things carefully because finding them was so easy.

New mail. In my browser, Proton often didn’t show new messages until I refreshed the page. On Fastmail new mail turned up straight away, on my phone too, without the app eating my battery.

Mail apps. With Proton, Apple Mail and Thunderbird meant installing Bridge, keeping it running and sorting it out when it stopped. With Fastmail they just worked, with no helper app at all.

Design. I take design seriously. If an app doesn’t give me the wow factor, no feature list will win me over. Fastmail is modern, very fast and easy to find your way around. Proton has come a long way since its early days, but it still feels a little clunky to me.

Focus. Proton has grown into a whole suite of products, and I haven’t always agreed with that direction. Most people don’t need all of them, and in my view more products means more to support, more that can go wrong and more that ends up in the price. Fastmail sticks to email, and everything just works as it should.

On the plus side, Proton’s apps are clean and easy to use, and everything fits together nicely with its calendar, drive, VPN and password manager. If you already use Proton Pass or Proton VPN, that counts for a lot.

Domains, addresses and prices

I look after several domains, and this is where the two are furthest apart. Proton’s Mail Plus plan allows one of your own domains and Proton Unlimited allows three, so my setup kept pushing me towards the more expensive plans. Fastmail lets you add up to 100 domains to one account, with users and aliases on any of them and a catch all for addresses that don’t exist. If you’re wondering why you’d want your own domain at all, have a read of why using your own email domain makes sense.

Proton’s prices are the sterling figures shown to a UK visitor on 7 October 2026 and include VAT. Fastmail lists dollars and adds VAT or sales tax at checkout based on your address, so it costs a little more than the figure shown. Unlimited bundles VPN, Drive, Pass and more, so if you only want email you pay for a lot you won’t use. Prices do change, so check both pricing pages before you buy.

Both have a way of giving each website its own address. Fastmail calls it Masked Email and Proton calls its version hide-my-email aliases. Masked Email was easily my most used Fastmail feature. I made the addresses straight from sign up forms through my password manager, and when a site got breached or started spamming me, I just switched that one address off. I compare the idea with throwaway inboxes in masked email vs disposable email.

Support

When it’s your main inbox, getting a quick answer matters. Only on rare occasions did I wait longer than a few hours for a reply from Fastmail, and the answers were friendly and knowledgeable. With Proton it was mixed. I’ve had slow replies, and a partner query I sent went unanswered for months. That’s my experience rather than proof of a pattern, but it did play a part in my move.

The law and where your mail is held

Fastmail is an Australian company. Australia is part of the Five Eyes intelligence alliance, and its laws include the Assistance and Access Act. Because Fastmail holds the keys to your stored mail, a valid legal order for a particular account could make it hand over readable messages.

Proton is based in Switzerland, outside both the US and the EU. With zero access encryption, a Swiss court order can only get stored messages in encrypted form, plus account details. That is a real advantage, but not an absolute one. Proton has said itself that under Swiss law it can be forced to collect information, such as an IP address, on an account under criminal investigation, and it has done so before. Encryption can’t hide who you are from a provider that logs it.

Both companies publish transparency reports, and I’d encourage you to read them.

The two aren’t directly comparable, because the companies count differently and have very different numbers of users, and Proton’s figures don’t say what was handed over. What they do show is that both respond to valid legal orders, which is why it matters what each one is able to hand over.

So it comes down to who you’re protecting yourself from. If it’s advertisers and data brokers, both do the job. If it’s a breach of the provider’s servers, or legal pressure from a government, zero access gives you more protection. For a wider look at this, see Swiss vs German email privacy.

Why Proton still has a special place with me

None of this is a knock on Proton. I followed its early days closely, including the long DDoS attack that left the service unusable for days. The lengths its engineers and founder went to in order to get back online were admirable. Plenty of companies would have folded. Proton came back, and that is a big part of why so many people trust it.

It’s also why I would never tell someone with a genuine need for zero access to look elsewhere, and why I still keep a Proton address myself. My preference for Fastmail is about everyday use, not about doubting what Proton is trying to do.

What I liked and what to be aware of

Which one I would pick

Neither is better for everyone. If you are a journalist, an activist or anyone who genuinely needs the people who run your email to be unable to read it, I would pick Proton and accept the trade offs. That’s exactly why I still keep a Proton address.

For everyone else, and especially if you run more than one domain or like using your own mail app, I would pick Fastmail. It was the best pure email service I’ve used, and I still miss it. Proton has a free plan and Fastmail has a free trial of up to 30 days, so you can try both before paying. If you’re also weighing up HEY, have a read of HEY vs Fastmail.

Questions people ask

Is Proton Mail more private than Fastmail?

For the mail stored in your account, yes. Proton can’t read your stored messages and Fastmail can. Neither makes money from adverts, so against advertisers and data brokers they do a similar job, and neither can hide who you email and when.

Is Fastmail better than Proton Mail?

For everyday use, I think so. It’s faster, works with any mail app and its support replies quickly. Proton is better if you need zero access encryption.

Which is better for your own domains?

Fastmail, by a long way. It allows up to 100 domains on one account. Proton Mail Plus allows one and Unlimited allows three.

Can I use Proton Mail with Apple Mail, Outlook or Thunderbird?

Yes, through Proton Bridge, an app on your computer that does the decrypting and passes your mail to the mail app. It needs a paid plan. Fastmail works with these apps directly over IMAP, JMAP, CalDAV and CardDAV.

Where does Fastmail store my data?

In the US by default. Since August 2026 you can choose the EU as your main region, stored in Amsterdam, but a copy and the backups stay in the US, and Fastmail doesn’t guarantee data stays only in the EU.

Which is cheaper?

Proton Mail Plus was listed at £3.19 a month on 12 month billing, and Fastmail Individual at $5 a month billed yearly, when I checked in October 2026. They differ in storage, currency and what’s included, so compare the plans you actually need.

Do I need end to end encryption for email?

Not for most people. Fastmail argues it adds little for most users, and email still shows who you email and when whatever you do. If you really need it, Proton, PGP or a different app such as Signal are the usual answers.

Disclosure: the Fastmail and Proton buttons are referral links. If you sign up through them, I may earn a commission at no extra cost to you. My opinions are my own. Sources: Fastmail pricing; Fastmail: domains; Fastmail: security; Fastmail: EU data region; Fastmail transparency report; Proton Mail pricing; Proton Mail Bridge; Proton transparency report.