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Mailbird Support
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📄 Overview

If Mailbird can't authenticate with your email provider, this guide walks you through the most common fixes. Authentication errors usually come with a specific cause. Scroll to the section that matches what you're seeing.

🔗 Jump to your issue

🛠️ General troubleshooting steps

Try these steps first. They fix most authentication problems:

1. Check your credentials

Ensure your email address and password are entered correctly. Even a single typo or trailing space will cause authentication to fail.

2. Whitelist Mailbird in your security software

Your antivirus, firewall, or other security software may be blocking Mailbird from reaching the mail server.

  • Whitelist Mailbird in your antivirus or security settings.
  • Or temporarily disable the software and try adding the account again.

3. Disable VPN temporarily

VPNs sometimes route traffic in ways that break authentication. Disable the VPN and try connecting again.

4. Confirm IMAP is enabled on your account

Many providers disable IMAP by default. See How to enable IMAP for your email account in Mailbird for per-provider steps.

📧 Provider-specific fixes

Gmail / Google Workspace

  • Ensure OAuth2 is selected as the authentication method.
  • Google no longer supports Username and Password for third-party apps like Mailbird. See Google's announcement.
  • If you see Application-specific password required or Web login required, your account has 2-Step Verification enabled. You must use an app password or OAuth2.

Outlook.com / Hotmail / Live (personal Microsoft accounts)

  • Use OAuth2 as the authentication method. Personal Microsoft accounts require it.
  • Ensure IMAP is turned on in Outlook settings under Mail → Forwarding and IMAP.
  • If you see User is authenticated but not connected, IMAP is disabled for your account. Enable it there, then re-add the account.

Microsoft 365 / Exchange Online (work or school accounts)

  • Use OAuth2. Basic authentication is no longer supported by Microsoft.
  • If you see Authentication Unsuccessful when sending, your admin must enable Authenticated SMTP for your mailbox.
  • For the best experience, we recommend using the Exchange protocol over IMAP for Microsoft 365 accounts when available.

Yahoo / AOL

  • Try OAuth2 first.
  • If OAuth2 fails, generate an app password and use it with Username and Password authentication instead of your regular account password.

iCloud

  • Generate an app-specific password from your Apple ID account. Two-factor authentication must be enabled.
  • If you use an alias or custom domain, click Edit server settings after entering the password. In both incoming and outgoing settings, set the username to your primary Apple ID or iCloud email.

Zoho Mail

  • Personal accounts: use imap.zoho.com as the IMAP server.
  • Business accounts: use imappro.zoho.com.
  • If two-factor authentication is enabled, create an app-specific password.

BT Internet

  • Occasionally passwords stop working even if entered correctly. A common workaround is to log in to BT webmail, reset your password, then add the account again.

⏱️ Too many requests / rate limit / throttled

The server is telling Mailbird to slow down, usually because too many login attempts or sync requests happened in a short time.

  • Wait 15 to 30 minutes before trying again. Most providers lift rate limits automatically.
  • Reduce simultaneous connections. If you access this account from multiple devices, some providers enforce a connection cap. Try signing out on a secondary device.
  • Remove the account and re-add it after the cooldown period. Repeated retries with wrong credentials can extend the lock

📊 Bandwidth limit exceeded

Your provider has hit a daily send, receive, or API usage cap:

  • Gmail: Google enforces daily sending and IMAP bandwidth limits. See Google's bandwidth limits. Wait 24 hours for the limit to reset.
  • Other providers: Most limits reset daily. Avoid bulk-downloading or bulk-sending if you're close to the cap.
  • If it happens repeatedly, your provider may have flagged unusual activity. Contact them directly.

🔒 Your account is locked or temporarily disabled

The provider has locked your mailbox, usually due to suspicious activity or too many failed logins. You must unlock it through your provider's website:

  • Sign in to your provider's web interface.
  • Look for a security challenge, unlock link, or CAPTCHA prompt.
  • Complete any verification steps your provider asks for.
  • Once unlocked, wait a few minutes, then try adding the account in Mailbird again.

If the lock persists, contact your email provider's support team. This is controlled on their end, not in Mailbir

⚠️ Server is temporarily unavailable / capacity issues

This is an issue on the provider's side, not yours:

  • Check your provider's status page.
  • Wait 10 to 15 minutes and try again.
  • If the status page shows no incident but the error persists, try connecting from a different network to rule out a local issue.

🤝 Still need help?

If you've worked through the relevant section and still can't connect, submit a support ticket and include:

  • Your email provider (for example Gmail, Outlook.com, or company Microsoft 365)
  • The exact error message shown in Mailbird
  • Whether you're using OAuth2 or Username and Password authentication
  • A screenshot of the error if possible

Our Customer Happiness Team will be happy to help.

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