Proton Mail SMTP Configuration
Use these exact values when configuring any email client or application to send through Proton Mail servers.
| Parameter | Value |
|---|---|
| SMTP Host | 127.0.0.1 (via Proton Mail Bridge) |
| SMTP Port | 25 or 587 (via Proton Mail Bridge) |
| Encryption | TLS/STARTTLS via Proton Mail Bridge |
| Username | Your full Proton Mail address |
| Password | Proton Mail Bridge application password |
Note: Proton Mail does not expose direct SMTP access to external applications from their servers. Sending from third-party apps requires the Proton Mail Bridge application, which runs locally and provides IMAP/SMTP access using your Proton Mail credentials.
Step-by-Step Setup
Proton Mail requires the Bridge application for SMTP access. Follow these steps in order.
1. Download Proton Mail Bridge
Download and install Proton Mail Bridge from the Proton website. Bridge is available for Windows, macOS, and Linux. A paid Proton Mail plan is required to use Bridge.
2. Log In and Configure
Open Bridge and log in with your Proton Mail credentials. Bridge will display local IMAP and SMTP credentials (host: 127.0.0.1, ports 25/587 for SMTP).
3. Generate App Password
In Proton Mail Bridge settings, generate an app-specific password for your email client. Use your Proton Mail address as the username and this app password for authentication.
4. Configure Your Application
Point your email application at 127.0.0.1 as the SMTP host, using port 587 with TLS and your Bridge credentials.
Common Errors and Solutions
Most Proton Mail SMTP issues relate to Bridge configuration. Here's how to fix them quickly.
Bridge Not Running
SMTP access through Proton Mail requires Bridge to be running in the background. Start Bridge, log in, and ensure it shows "Connected" status before attempting to send email.
Wrong Host/Port
Proton Mail Bridge uses local host 127.0.0.1, not smtp.protonmail.com. Check the Bridge interface for the correct local port numbers, which may vary between setups.
Authentication Failed
You must use an app password generated by Bridge, not your Proton Mail account password. Generate a new app password in Bridge settings if authentication is failing.
No Paid Plan
Proton Mail Bridge is only available to paid Proton Mail subscribers. Free accounts cannot use Bridge or any form of SMTP/IMAP access to Proton Mail.
Best Practices for Proton Mail SMTP
Keep your account secure and your messages private with these recommended approaches.
Keep Bridge Updated
Proton Mail Bridge is updated regularly. Keep it updated to receive security patches and bug fixes. Outdated Bridge versions may cause connection issues.
Use Separate App Passwords
Generate unique app passwords for each application using Proton Mail via Bridge. This allows you to revoke access for individual apps without affecting others.
Enable Auto-Start
Configure Proton Mail Bridge to start automatically with your operating system. This ensures SMTP access is always available without manual intervention.
Bridge Runs Locally
Remember that Proton Mail Bridge runs on your local machine. SMTP access only works when Bridge is running and your computer is connected to the internet.
When Proton Mail SMTP Falls Short
Proton Mail's Bridge-based SMTP is designed for privacy-conscious individuals using standard email clients. It is not suitable for application-to-email sending in production environments. The local Bridge requirement means you can't send emails when Bridge isn't running, and there's no webhooks or delivery analytics. A dedicated email API provides reliable, always-on infrastructure with full observability.
For teams needing privacy-respecting email infrastructure at scale, SMTP relay services offer a better alternative. Learn more about email deliverability and why consistent sender reputation matters for inbox placement.
Frequently Asked Questions
Does Proton Mail support direct SMTP access?
No. Proton Mail does not provide direct SMTP access to external applications. All third-party email client access goes through Proton Mail Bridge, which runs locally on your device and provides IMAP/SMTP via localhost.
Is Proton Mail Bridge free?
No. Proton Mail Bridge requires a paid Proton Mail subscription. Free Proton Mail accounts cannot use Bridge or any external IMAP/SMTP access.
Can I use Proton Mail SMTP for automated emails?
Proton Mail Bridge can technically be used for automated emails, but since it runs locally, automation would only work when your computer is on and Bridge is running. This is not practical for most production use cases.
What are Proton Mail's sending limits?
Proton Mail sending limits vary by plan. Generally, limits are 100-200 messages per hour for paid accounts. These limits are not designed for high-volume application email sending.
Does Proton Mail support custom domains?
Yes, with a paid Proton Mail plan you can add custom domains. However, SMTP access for custom domains still routes through Proton Mail Bridge on your local machine.
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