Proton Mail addresses (@proton.me, @pm.me, and legacy @protonmail.com) do not accept standard SMTP, IMAP, or POP3 connections directly. End-to-end encryption is the reason: Proton’s servers only hold ciphertext, so a mail client that connects with a normal username and password would receive unreadable messages. The workaround Proton provides is Proton Mail Bridge, a small desktop app that runs a local IMAP and SMTP server on your computer and transparently decrypts messages between Proton’s servers and your mail client. This guide covers the exact settings Bridge exposes, the plan tier required, and the free-plan limitation that blocks third-party clients entirely.
Setup gotcha
Bridge requiredPaid plans only
Proton Mail does not offer direct IMAP, POP3, or SMTP access. Third-party mail clients (Outlook, Thunderbird, Apple Mail, K-9 Mail, FairEmail, or any SMTP relay) must go through Proton Mail Bridge, a desktop application from Proton that runs a local encryption gateway. Bridge is available only on Proton Mail Plus, Proton Unlimited, Proton Business, or higher paid plans. The Proton Mail Free plan does not include Bridge access: free-tier users cannot use any external mail client at all and are limited to webmail at mail.proton.me and the official Proton mobile apps. Reference: SMTP authentication.
Quick reference: Proton Mail Bridge server settings
Bridge installs on your desktop (Windows, macOS, Linux) and exposes a local IMAP and SMTP endpoint at 127.0.0.1. Both protocols use STARTTLS and full-address authentication with a Bridge-generated password (not your Proton account password). Proton Mail Bridge does not support POP3: only IMAP and SMTP are provided. Use these settings after installing Bridge and adding your Proton account inside the Bridge app.
| Protocol | Server | Port | Encryption | Auth |
|---|---|---|---|---|
| SMTP | 127.0.0.1 | 1025 | STARTTLS | Full address + Bridge password |
| IMAP | 127.0.0.1 | 1143 | STARTTLS | Full address + Bridge password |
| POP3 | Not supported | N/A | N/A | Use IMAP instead |
Proton Mail SMTP settings via Bridge
Proton Mail SMTP runs at 127.0.0.1 on port 1025 with STARTTLS. The Bridge app assigns a distinct Bridge password (not your Proton account password) that you paste into the mail client’s SMTP authentication field. Username is the full Proton email address you added to Bridge (for example you@proton.me). Outgoing messages are encrypted locally by Bridge before being sent to Proton’s servers, so the mail client only sees a plaintext connection to localhost.
Port 1025 is the Bridge default. If it is already in use by another application (VoIP, streaming, another mail service), Bridge shows a “port already occupied” error. The fix is in Bridge Settings then Advanced then Default ports: increase the port number by one (1026, 1027, etc.) until the conflict clears, then update the mail client to match. Never use port 465 or 587 for Proton: those would try to reach a public Proton SMTP server that does not exist.
Proton Mail IMAP settings via Bridge
Proton Mail IMAP runs at 127.0.0.1 on port 1143 with STARTTLS. Same Bridge-generated password as SMTP, same full-address username. Bridge decrypts messages transparently as your mail client pulls them via IMAP, so the client sees plain email content while Proton’s servers still only hold ciphertext at rest.
IMAP folder sync mirrors the Proton Mail folder structure (Inbox, Archive, Drafts, Sent, Spam, Trash, plus custom folders). Labels in Proton Mail webmail appear as IMAP folders. Storage limits are per Proton plan: Mail Plus 15 GB, Unlimited 500 GB, Business 500 GB per user. Bridge pulls only what your client requests, so large accounts do not force a full local download.
POP3 is not supported
Proton Mail Bridge does not expose POP3. This is a deliberate design choice: POP3 downloads and (by default) removes messages from the server, which conflicts with Proton’s encrypted-at-rest architecture and multi-device sync guarantees. If your existing setup requires POP3 (older mail client with no IMAP support), the practical answer is to switch to IMAP or use webmail. There is no configuration flag or paid tier that unlocks POP3 for Proton Mail.
Free plan blocks all third-party clients
Proton Mail Free does not include Bridge access. Free-plan users cannot configure Outlook, Thunderbird, Apple Mail, or any mobile mail app against their Proton account. The only supported ways to read Proton mail on a free plan are the webmail at mail.proton.me and the official Proton Mail apps for iOS and Android. This is a hard restriction enforced at the Proton API level, not a Bridge configuration issue: Bridge simply refuses to activate a free account. The upgrade path is Proton Mail Plus (~4.99 EUR/month with annual billing), which is the cheapest tier that includes Bridge.
If your requirement is standard IMAP/SMTP access without a bridge app, other privacy-focused providers work with any mail client out of the box: Runbox (Norway, paid from ~$1.66/month), Mailbox.org (Germany, from 1 EUR/month), Posteo (Germany, from 1 EUR/month), or Fastmail (Australia, from $3/month). These trade Proton’s default end-to-end encryption for direct protocol support and lower entry price.
Installing Proton Mail Bridge
Download Bridge from proton.me/mail/bridge (Windows, macOS, or Linux). Install and launch the app, then sign in with your Proton account credentials plus the two-factor code if 2FA is enabled. Bridge initializes a local mail store on first sync, which can take several minutes for accounts with large mailboxes. Once initialization completes, Bridge shows an “Account: Active” status and displays the SMTP and IMAP settings above along with a Bridge-generated password for each configured mail client.
Each mail client gets its own Bridge password. You generate a separate password in Bridge for Thunderbird, another for Outlook, another for a mobile app, and so on. Passwords are not reusable across clients and are revocable individually. If you rotate your Proton account password, Bridge automatically re-syncs but the per-client Bridge passwords stay valid until you rotate them explicitly.
IMAP, POP3 and SMTP Integration into Gmail
Configure Gmail with external IMAP/POP3/SMTP to send/receive emails from your custom domain through Gmail’s interface. Perfect for professionals managing multiple accounts in one place.
- Google Account β Security β App passwords (2-Step Verification must be enabled).
- Generate App Password for “Mail” β copy 16-character password.
- Gmail β Settings β See all settings β Forwarding and POP/IMAP.
- Enable IMAP β Save Changes.
- Incoming (IMAP):
[IMAP SERVER]:993 SSL| Outgoing (SMTP):[SMTP SERVER]:587 STARTTLS. - Use your full email + App Password (not regular password) for authentication.
β Gmail Result: Send/receive custom domain email directly in Gmail interface with full search/folder integration.
WordPress SMTP Plugin Configuration (WP Mail SMTP + MailPoet)
Configure SMTP in WordPress to fix email delivery issues and prevent spam folder placement. WP Mail SMTP and MailPoet ensure reliable transactional emails, contact forms, and newsletters deliver successfully.
- Install and activate WP Mail SMTP or MailPoet plugin from your WordPress dashboard.
- Navigate to WP Mail SMTP β Settings or MailPoet β Settings β Sending tab.
- Select “Other SMTP” as your mailer method from the dropdown.
- Enter SMTP settings with Port
587and STARTTLS encryption (when available). - Input your full email address and password in the authentication fields.
- Click Save Settings and send a test email to verify the configuration works.
β Result: WordPress contact forms, user registrations, and newsletter emails now deliver reliably via your SMTP server.
This configuration includes these plugins and tools within WordPress:
- HappyForms
- Elementor Forms
- Gravity Form
- WooCommerce Checkout Form
- Contact Form by BestWebSoft
- Fluent Forms
- Contact Form 7
- WPForms
- Ninja Forms
- Default WordPress Reg Form
- Forminator Forms
- Formidable Form
- WordPress Comment Form
- Mail Mint Form
Thunderbird OAuth2 Email Setup (IMAP + SMTP)
Secure IMAP & SMTP using OAuth2 token authentication in Thunderbird. This modern method eliminates password storage for enhanced security.
- Open Thunderbird β Account Settings β Account Actions β Add Mail Account.
- Enter your email address and click Continue to begin setup.
- Select IMAP protocol and choose OAuth2 authentication method.
- Thunderbird opens a browser window β log in to your provider β Grant access permissions.
- Automatic configuration applies: Incoming: use the IMAP server address from the settings table above, port 993, SSL
- Click Done β Thunderbird begins syncing folders and emails immediately.
OAuth2 advantage: Token-based authentication enhances security over traditional password methods while maintaining full functionality.
Outlook IMAP, POP3 & SMTP Setup (Auto + Manual)
Outlook configuration supports both automatic server detection and manual IMAP/POP3/SMTP settings for complete control over your email setup.
π Auto Setup (Recommended):
- Go to File β Add Account β Enter your email address + password.
- Outlook automatically detects IMAP, POP3, and SMTP server settings.
- Click Connect β setup completes in approximately 30 seconds.
βοΈ Manual Setup (Advanced Users):
- Authentication: Use your full email address + password for both servers
BlueMail Two-Factor Authentication + OAuth2 Setup
BlueMail security setup combines OAuth2 authentication with two-factor authentication (2FA) for maximum account protection.
- Open BlueMail β Account Settings β Security β Enable Two-Factor Authentication.
- Link your phone number or authenticator app for 2FA verification codes.
- Add email account β Choose OAuth2 or manual server configuration.
- Enter server details from the table above
- Complete login with 2FA code β enhanced security layer activated.
Apple Mail IMAP Configuration (iCloud + Manual)
Setup IMAP in Apple Mail for seamless synchronization across Mac, iPhone, and iPad devices with full folder support.
- Open Apple Mail β Mail β Add Account β Other Mail Account.
- Enter your name, email address, and password β click Continue.
- Select IMAP account type β Incoming server.
- Next: Outgoing server
- Click Sign In β Mail verifies settings and begins folder synchronization.
iOS Mail App Setup (iPhone/iPad)
iPhone/iPad Mail configuration syncs IMAP folders across all Apple devices with native push notifications.
- Go to Settings β Mail β Accounts β Add Account β Other.
- Enter name, email, password β Next.
- Account Type: IMAP β Incoming:
[IMAP SERVER]Port993SSL. - Enter your outgoing SMTP server and port.
- Next β Save β iOS verifies and syncs immediately.
Push enabled automatically: new emails appear instantly on Lock Screen.
Android Mail App Configuration
Android Gmail/Email app setup works with any IMAP/SMTP provider for native device integration.
- Go to: Settings β Accounts β Add Account β Email (or Gmail app).
- Enter email + password β Next.
- Account Type: IMAP
- Outgoing server details β Require authentication.
- Next β Sign In β Android syncs contacts/calendar if enabled.
Sync interval: 15min default (battery optimized) – change in Account Sync settings.
eM Client Manual IMAP & POP3 Sync Configuration
Configure your email settings on eM Client with either automatic setup or through precise IMAP/POP3 server settings for reliable email synchronization and full folder support.
- Click New Account β Mail
Authentication requires full email address + password for both incoming and outgoing servers.Click Next β Finish β Send/Receive All Folders to begin synchronization.
Mailbird OAuth2 IMAP & SMTP Integration
Secure Mailbird setup using OAuth2 authentication eliminates password storage while providing full IMAP/SMTP functionality.
- Mailbird β Add Account β Enter your email address to begin.
- Choose Manual Setup β OAuth2 authentication method from options.
- Browser opens your provider’s login page β enter credentials β Authorize Mailbird.
- Mailbird receives access token and automatically configures IMAP/SMTP servers.
- Setup completes β full email synchronization begins automatically.
Mailspring OAuth2 IMAP Configuration
Mailspring OAuth2 setup provides secure email access without storing passwords directly in the application.
- Add new email account β Select Custom IMAP configuration option.
- Incoming
IMAP SERVERand outgoingSMTP SERVER. - Mailspring prompts OAuth2 authorization via browser window for secure login.
- Log into your provider account and grant Mailspring access permissions.
- Mailspring automatically manages authentication tokens β seamless email access established.
Postbox Manual IMAP Synchronization
Postbox IMAP setup with manual synchronization control for precise email folder management and immediate updates.
- Add IMAP account β Enter IMAP Server details.
- Outgoing SMTP with full email authentication.
- Postbox connects and displays folder structure automatically.
- Right-click any folder β Get Messages for immediate manual synchronization.
- Manual sync updates local mailbox instantly with server changes (read status, deletions, organization).
SendBlaster SMTP Configuration (Bulk Email)
Bulk email SMTP configuration in SendBlaster requires precise server authentication for reliable campaign delivery.
- Open SendBlaster β Settings β SMTP Configuration section.
- Enter SMTP Server and Port: do not forget to Enable TLS encryption.
- Authentication: Your full email address + password (required).
- Click Test Connection β verify green success indicator appears.
- Save settings β SendBlaster ready for bulk email campaigns and newsletters.
MailJerry IMAP Real-Time Synchronization
MailJerry IMAP setup enables real-time access to email folders stored on your provider’s server across all devices.
- Incoming Server and encryption required.
- Authentication: Full email address + password for secure connection.
- Enable real-time folder synchronization settings in MailJerry preferences.
- Folders update instantly with new messages, read status, and deletions across devices.
Clean.email OAuth2 Synchronization Setup
Clean.email OAuth2 setup provides secure mailbox access without sharing passwords directly with the application.
- Add new account β Select OAuth2 authorization method.
- Your provider opens login portal β enter credentials securely.
- Grant Clean.email permissions for email read/write access.
- OAuth2 token enables real-time message management, filtering, and organization.
- Setup complete β Clean.email maintains secure, ongoing mailbox synchronization.
Common IMAP/POP3/SMTP Troubleshooting
- Authentication failed: Always use your complete email address, never just the username portion.
- Port blocked by ISP: Try alternative SMTP port as fallback.
- SSL certificate errors: Ensure certificate validation is enabled in client settings.
- Slow or no IMAP sync: Check folder subscriptions and enable all folders in client settings.
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Frequently asked questions
Why can’t I use Outlook or Thunderbird directly with Proton Mail?
Proton Mail encrypts every message at rest on Proton’s servers. A direct IMAP or SMTP connection would receive ciphertext, which the mail client cannot decode. Proton Mail Bridge is the workaround: it runs a local IMAP and SMTP server that handles decryption transparently, so your mail client speaks plain protocols to localhost while Proton’s servers only ever hold encrypted content. Bridge is a paid-plan feature.
Can I use Proton Mail on the free plan with a mail client?
No. Free-plan accounts cannot activate Proton Mail Bridge, and there is no other supported way to configure Proton with a third-party client. Free users are restricted to webmail at mail.proton.me and the official Proton Mail apps for iOS and Android. The cheapest upgrade path is Proton Mail Plus at around 4.99 EUR/month with annual billing.
What ports does Proton Mail Bridge use?
Bridge exposes SMTP on 127.0.0.1 port 1025 and IMAP on 127.0.0.1 port 1143, both with STARTTLS. These are non-standard ports; some corporate mail clients or endpoint security tools may block them by default. If a port is already in use by another app, Bridge lets you increment the port number in Settings then Advanced then Default ports.
Does Proton Mail support POP3?
No. Bridge exposes IMAP and SMTP only. POP3 conflicts with Proton’s encrypted-at-rest and multi-device sync architecture, and there is no configuration flag or paid tier that adds POP3 support. Use IMAP instead: it works with every mail client that would have used POP3.
Can I use Proton Mail with mobile mail clients?
Only via the official Proton Mail apps for iOS and Android, or via a client that proxies through Bridge on a desktop that stays online. Third-party mobile mail apps (K-9 Mail, FairEmail, Apple Mail on iPhone, Gmail app) cannot connect to Proton directly because Bridge does not run on mobile. The two practical options are Proton’s official app or forwarding Proton mail to another provider that does support mobile IMAP.
What is the Bridge password and how is it different from my Proton account password?
Bridge generates a distinct password per mail client you configure. This Bridge password is what you paste into Outlook, Thunderbird, or Apple Mail, not your Proton account password. The separation lets you revoke access from a specific mail client (by regenerating that client’s Bridge password) without affecting your Proton account credentials or 2FA setup. Rotating your Proton account password does not invalidate existing Bridge passwords.
How does Proton Mail compare to other privacy-focused mail providers?
Proton Mail (Switzerland) uses OpenPGP by default for messages between Proton users and offers PGP for external contacts via Bridge. Runbox (Norway) offers standard IMAP/SMTP/POP3 without a bridge, at low entry pricing. Mailbox.org and Posteo (both Germany) offer standard protocols with optional PGP for around 1 EUR/month. Fastmail (Australia) is paid-only and uses standard protocols without server-side encryption. Choose Proton for default E2E encryption if you can live with Bridge; choose Runbox, Mailbox.org, or Posteo for direct third-party client access without a bridge app.
Where is Proton Mail webmail?
Webmail is at mail.proton.me. The old mail.protonmail.com URL still redirects there. Bookmark it to avoid phishing pages that impersonate the login. Access from webmail works on any Proton plan (including free), unlike Bridge which requires a paid tier.
About this guide
These Proton Mail Bridge server settings were verified against Proton’s official documentation at proton.me/mail/bridge and proton.me/support/imap-smtp-and-pop3-setup in July 2026. Port numbers and hostnames rarely change but the plan tier required for Bridge is worth re-verifying at Proton’s pricing page before purchase, as Proton has restructured its consumer tiers twice since 2022. SMTPedia re-verifies each provider quarterly and after any announced infrastructure change.
About the Author
Alaa Β· LinkedIn
Email infrastructure specialist with 8+ years of hands-on experience in SMTP, deliverability, and email verification. Iβve configured and troubleshot mail systems across Postfix, Exchange, and cloud relays, managed IP reputation and warmup campaigns, and built verification pipelines processing millions of addresses. My work spans DNS authentication (SPF, DKIM, DMARC, BIMI), bounce handling, blocklist monitoring, and compliance frameworks including CAN-SPAM and GDPR. I write every article on SMTPedia to give email professionals, developers, and marketers the accurate, RFC-grounded reference they need.
About SMTPedia
SMTPedia is an independent email industry reference covering SMTP, IMAP, POP3, email deliverability, marketing platforms, DNS authentication, and email verification. Every article is researched from official provider documentation, IETF RFCs, and industry best practices. Settings and configurations are verified quarterly.
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