Proton Mail (ProtonMail): what it is, how it works and what the free account includes
The Swiss encrypted email service: what it protects, what the free plan includes and how to use it in other email clients
Proton Mail is an encrypted email service from the Swiss company Proton: a @proton.me address whose messages not even the company itself can read.
Here’s how its encryption works, what the free account includes, how to use it in other email clients and what its limits are.
What is Proton Mail?
It’s an email service built for privacy. It was created in 2014 by a team of scientists who met at CERN, and today it is run by Proton AG from Geneva.
Until 2022 it was written ProtonMail, as one word. Addresses can end in @proton.me or @protonmail.com, and both work the same way.
Proton also offers a VPN, cloud storage, a password manager and a calendar. In February 2026 it announced more than 100 million users across all its services.
How does its encryption work?
The difference from Gmail or Outlook lies in who can read your messages.
- Between Proton users, encryption is end-to-end: only the sender and the recipient can see the content.
- Your stored messages use zero-access encryption: Proton stores them but can’t open them.
- If you write to another provider, the message goes out as a regular email, unless you protect it with a password.
One thing isn’t end-to-end encrypted: the subject line, the sender and the recipient, which are needed to deliver the email.
Do you send your newsletter from Proton Mail?
With 150 messages a day, you can’t reach your whole list. With Mailrelay you send to all your subscribers, with statistics and automatic unsubscribes. Free account with up to 80,000 emails a month.
What does the free account include?
The free account works well for light personal use, but it has clear limits:
| Feature | Free account |
|---|---|
| Email storage | 500 MB, expandable to 1 GB |
| Addresses | 1 (@proton.me) |
| Messages sent | 150 a day |
| Folders and labels | 3 of each |
| Attachments | Up to 25 MB |
| Custom domain | No |
| Use in Outlook or Thunderbird | No (requires a paid plan) |
Watch out for inactivity. A free account you don’t use for 12 months may be deleted, along with all its content. Proton warns you first, but it’s worth logging in from time to time.
What paid plans are there?
Paid plans remove the daily limit and add storage, more addresses and a custom domain.
| Plan | Who it’s for | Highlights |
|---|---|---|
| Mail Plus | Personal use | 15 GB, 10 addresses and 1 custom domain |
| Proton Unlimited | Personal use with all services | 500 GB, 15 addresses and 3 domains |
| Duo and Family | Couples and families | Several accounts with shared storage |
| Business plans | Teams | Email on your domain, plus admin tools |
Prices vary by billing period and currency: check them on Proton’s website. With a business plan, it works as an encrypted corporate email.
How do you use Proton Mail in Outlook or Thunderbird?
The service doesn’t support POP3 or direct IMAP and SMTP access, because its servers can’t read your messages. To use it in an email client you need Proton Mail Bridge, an app for Windows, Mac and Linux included in the paid plans.
Bridge encrypts and decrypts on your computer and creates a local server:
| Setting | Incoming (IMAP) | Outgoing (SMTP) |
|---|---|---|
| Server | 127.0.0.1 | 127.0.0.1 |
| Port (default) | 1143 | 1025 |
| Encryption | STARTTLS | STARTTLS |
| Password | The one Bridge generates | The same one |
Don’t use your Proton account password: Bridge creates a different one for each client.
Proton Mail, Gmail or Outlook?
It depends on what matters more to you: privacy or convenience.
| If… | Go for |
|---|---|
| Privacy comes first | Proton Mail |
| You want 15 GB free and lots of integrations | Gmail or Outlook |
| You use an iPhone, iPad and Mac | iCloud Mail |
| You need email for your business | Proton for Business, Google Workspace or Microsoft 365 |
| You just want to sign up on a website without giving out your address | An alias or a temporary email |
It’s not a good idea. The free account is capped at 150 messages a day, and the paid plans are designed for personal and business email, not for sending to an entire list.
You also don’t get open and click statistics or unsubscribe management. And, by design, Proton doesn’t track what happens to your messages, which is exactly what a campaign needs to measure.
That’s what bulk email tools are for, and they respect each provider’s sending limits. And if your subscribers use Proton, they’ll receive your newsletters like any other email.
How Mailrelay helps you
With Mailrelay you send your newsletters to your whole list from your own address and an authenticated sending domain, without the daily cap of a personal email account.
The free account includes up to 80,000 emails a month and 20,000 contacts.
You get a visual editor, automations, open and click statistics, and automatic management of unsubscribes and bounces, with human support on every plan. All the details are on the pricing page.
Your private email, your newsletters with Mailrelay
Templates, automations and statistics, with human support on every plan.
Frequently asked questions about Proton Mail
These are the most common questions.
Is Proton Mail free?
Yes. It has a free account with 1 GB of storage and 150 messages a day. Paid plans add storage, addresses and a custom domain.
Are Proton Mail and ProtonMail the same thing?
Yes. In 2022 the company started writing it as two words, Proton Mail, when it brought all its services together under the Proton brand.
Is Proton Mail secure?
It’s one of the most private email services: it encrypts your stored messages and the ones you send to other Proton users. Even so, protect your account with two-step verification and watch out for phishing, as with any other email service.
Can I use my own domain?
Yes, with a paid plan. Mail Plus includes one custom domain, and the business plans include several.
Why can’t I set up Proton Mail in Outlook?
Because you need Proton Mail Bridge, which is only available on paid plans. With the free account, use the website or the official app.