IMAP

How to Migrate Thunderbird to Proton Mail? Step By Step Guide

By Admin

Updated: April 22, 2026 ~ 5 Minutes Reading

Table of Contents
Overview: The process to migrate Thunderbird to Proton Mail involves either setting up Proton Mail email in Mozilla Thunderbird via the Bridge Application. Or you can use a specialized Thunderbird to Proton Mail migration tool for direct & secure import with attachments and other attributes.

Business users with extreme data sensitivity prefer migrating to Proton Mail. This is because of its security protocols. Thus to centralize data users need to import emails from Thunderbird (local folder or configured account) into Proton Mail account. Here are exact follow along steps to transfer emails from Thunderbird to Proton Mail with tips to ease the process.

Prerequisites to Migrate Thunderbird to Proton Mail

  • Paid Proton Mail Account.
  • Proton Mail Bridge Application Installed & set up with the desired Proton Mail ID for import.
  • Stable internet connection.
  • Proton Mail Bridge connected to Thunderbird.
  • Ensure Proton Mail Mailbox has required storage space.

Manual Way to Import Thunderbird Emails to Proton Mail

Note: The steps given below are functional with all Thunderbird versions. However you will need to configure manually if you have a custom domain.

Phase 1: Connected Thunderbird to Proton Mail Account

  1. Open Mozilla Thunderbird on your computer.
  2. Click on the Hamburger Menu.
  3. Choose a New Account >> Email.
  4. Enter your name and @protonmail.com account.
  5. In password enter Proton Mailbox Password. (Locate At: Proton Mail Bridge >> Account >> Mailbox Details)

Note: Port details for manual Thunderbird configuration for Proton Mail are also located under Mailbox Details in Proton Mail Bridge Application.

Phase 2: Import Folder setup

You need to create an import folder under the Proton Mail account configured in Thunderbird.

  1. Right-click on the configured account.
  2. Choose a New Folder.
  3. Name the Folder (eg: ThunderbirdImport).
  4. Press Ok to Confirm.

Phase 3: Migrate Thunderbird to Proton Mail – Emails & Folders

For Custom Folder:

  1. Right-Click on the Folder.
  2. Choose Move To or Copy To.
  3. Select the new folder under Proton Mail account as destination.

For Built-In Special Folders – Inbox, Span, Sent, etc.:

  1. Open the Folder.
  2. Press Ctrl + A on the keyword to select all emails.
  3. Right Click >> Choose Move To or Copy To.
  4. Select the folder as destination.

Once the sync is completed you can access these emails in Proton Mail Bridge Application or via the Proton Mail Webmail

Drawbacks of Manual Approach to Migrate Thunderbird to Proton

Although it is native way to transfer emails the process falls shorts on certain terms making it less feasible way:

  • Extensive manual configuration steps. (often leads to failure)
  • Risk of data loss – due to human error & dependency on IMAP sync.
  • Only suitable for limited data – bulk transfer can be time taking.
  • Requires technical skills.

Thunderbird to Proton Mail Migration Tool – Automated & Safe Import

Thunderbird Migration Tool is a software application that directly fetches data from Thunderbird profile and transfers emails to the Proton Mail account. With the tool you can decrease the downtime with a significantly larger Thunderbird profile. Its easy-to-use interface makes the import accessible without any technical knowledge and functional with backed up Thunderbird data. Try the demo version for free Thunderbird emails to Proton Mail import – limited to 25 emails per folder.

Perform Thunderbird to Proton Mail Migration – User Steps

  1. Download, install, and open the tool.
    Launch Thunderbird to Proton Mail Migration Tool
  2. Choose to migrate the configured Thunderbird profile.
    Migrate Thunderbird configured Profile to Proton Mail account
  3. Preview folders & select the folders from Thunderbird.
  4. From the Saving option, choose IMAP.
    IMAP saving option for Proton Mail
  5. Enter the Proton Mail email address, App Password & IMAP host & Port Number (available in Mailbox Details in Proton Mail bridge Application)
  6. Press Next to start the import.

Why is an Automated Tool Recommended to Migrate Thunderbird to Proton Mail?

  • Bulk Data Handling: No restriction on mailbox size or profile size, the tool can handle enterprise level of data.
  • Secure Configuration: It uses the app password and the compliance with GDPR, CAPA & HIPAA ensures no data is saved locally or on another server.
  • Data Integrity: Import Thunderbird emails to Proton Mail including attachments, metadata, while maintaining the complete folder structure along with email header information such as date, time, sender-receiver details, etc.
  • Filter Option: Advanced filters based on date range, subject keyword and sender and receiver addresses.
  • Change Language Option: Multi-language option such as – English, French, and Swedish for better international accessibility.

The tool gives additional features like – log report generation with selection option from the backed up Thunderbird profile.

FAQ: Thunderbird to Proton Mail Migration

Q1: Is Thunderbird compatible with Proton Mail?
Yes, you can configure your Proton Mail account in Thunderbird, however, it is not directly possible via email address/password, but indirectly via mailbox details, after configuration in Proton Mail Bridge application.

Q2: Can I import Thunderbird emails to Proton Mail without Bridge?
No, due to Swedish data security and privacy laws, you cannot directly access ProtonMail accounts in third-party applications like Thunderbird. The configuration must go via the local addresses generated by the Proton Mail bridge application.

Q3: Can I import MBOX from Thunderbird to Proton Mail?
Yes. However, you first need to import MBOX into Thunderbird via ImportExport NG Tools or Thunderbird Import Tools, and then migrate imported MBOX emails to the Proton Mail account.

Need help migrating your Thunderbird data to Proton Mail account?

Get in touch with our Thunderbird experts via the live chat option available 24/7. Get assistance or request a customized feature in the application.