Connect Gmail to Proton Mail: what can Google still see?

Sender composes email using a linked personal Gmail address in Proton Mail. Linked Gmail address is the sender address. The recipient is someone else. By the routes described in the Proton documentation, delivery to a Proton recipient is end-to-end encrypted. Delivery to non-Proton recipient takes the path through Gmail servers, readable by Google.

This document references the Proton documentation and the Free account connection settings inspection. There's no Google account connected, no mail imported, no message delivery tested. Alex and conversations are fictitious.

We are a Proton affiliate and may earn commission on qualifying paid subscriptions through our referral links. A Free signup alone does not earn us commission.

This guide can be read without an account. You can inspect settings with an existing Proton account. Or you can begin with a Proton Mail Free (opens in a new tab). You can leave Gmail disconnected for setting inspection.

1. Separate an import from a connection

Import is copy: copying from your existing messages in Gmail to Proton Mail.
The connection to Gmail is for live mail: new messages from Gmail show up in Proton. The sender can also send from their Gmail address in Proton Mail.
You can either import or connect (or both) and it's your choice to do either of these two things.
For free, you can have 1 personal connection to Gmail.
For paid, you can have up to 3.
This includes any existing legacy forwarding connections.
(Google Workspace, custom domains aren't included with these personal account instructions.)
Read the latest migration instructions (opens in a new tab) before giving them access.

2. Keep the sender fixed and change the recipient

For this example we're just making things up. Alex composes two emails using Proton Mail. Both emails are sent from the same connected personal gmail account. The application and sender are the same.

First email. The recipient email address is in Sam's Proton account. This recipient email can be a Proton Mail address or it can be a Gmail email address that's connected to Sam's Proton account by using the Gmail connection.

Proton has documentation that shows end-to-end encryption of the email from Alex to Sam. We can't tell from the email domain (the domain you see on the email) what mail provider the recipient is using.

Second email. The email recipient is not using Proton. The email from Alex to the second recipient will go through Google (gmail) servers without end-to-end encryption. The email is readable by Google. It is in the Sent folder in gmail.

The examples we're making up here are based on documented paths for sending from Proton (opens in a new tab). We didn't test the delivery of the messages.

For receiving: if the email you've received in Gmail is forwarded to Proton it's been handled by Google. There's nothing you can do about the handling just by reading the email in Proton. From Proton's perspective, using the Gmail connection doesn't give Google access to the separate Proton inbox. Mail privacy policy (opens in a new tab).

3. Check two conversations you actually need

Pick a random every day e-mail conversation and a private e-mail conversation (before connection). Write down for each of these conversations:

1. Sender email address
2. Sending app
3. Recipient mail service. If you cannot find out, write 'unknown'.
4. Does the tracked path go via Google's servers?

Unknown recipient service does not mean e-2-e. For the conversation you want to protect, you can use password protected e-mail. You can send the password in a separate way.

Reminder case: fictitious Alex. Someone sends him a reminder (appointment) e-mail to Alex's Gmail address. First reminder arrives to Alex's Gmail inbox, then it gets forwarded to Alex's Proton inbox. This reminder goes through Google before it arrives to Alex's Proton inbox (before Alex reads it there). Alex can provide another e-mail address to the appointment sender. He can see which e-mail address gets the next reminder e-mail. (This is suggestion for actions. We didn't migrate.)

Just a Proton sending e-mail address doesn't mean e-2-e for someone (a person) who is not Proton. You can use password protected e-mail (free has password protected e-mail and you can provide the password separately). See how to use password protected e-mail. You can see there also limits for reply. E-mail subject line is not e-2-e by default. Don't put sensitive things to the subject line. Read from Proton (opens in a new tab) what are those e-2-e limits.

4. Inspect the setup before granting access

In the web version of the Proton Mail app, go to Settings > All settings > Import via Easy Switch. Check out the dedicated Imports and Connected emails sections. Take a look at the import option, what permissions Google wants and then consider whether or not you want to allow the connection.

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Imports and Connected emails

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Here's our screenshot with imports and connected emails in the Free account we looked at. (It's a crop of the setup screen with 0 import history, 0 connected addresses.) We didn't transfer anything. (If you don't see the connect option, for Proton there's a gradual rollout as per this announcement. (opens in a new tab) Note the specific limitation on the current help page: if you signed up to Proton via Proton VPN or Proton Pass using a Gmail address, you currently can't connect the same Gmail address. Check the latest advice on account conflict. (opens in a new tab) Don't remove any accounts for this guide.)

If the connection does not meet your privacy goal

Continue to use your Gmail at the same time as you're thinking about whether or not you want to connect it to Proton. You can continue using your Gmail account with no connection to Proton. Think about who you'd like to use another email address to write to you. Think about which discussions require a password-protected message. If you were to connect, you may find an older Gmail address easier to use for one inbox. But depending on the path of each discussion, you may or may not have more privacy.

If you're OK with one personal Gmail connection, then try out Proton Mail Free (opens in a new tab). Look at the setup before you OK'ing the Gmail to Proton connection. Don't get a paid Proton plan unless there's a specific limit stopping you from doing something you want to do. A promotional discount has no bearing on the send path.