Overview

If Mailbird can't authenticate with your email provider, this guide walks you through the most common fixes. Authentication errors usually have a specific cause, so start with the general checks below, then jump to the section that matches the error or provider you're seeing.

🔗 Jump to your issue

• General troubleshooting steps
• Provider-specific fixes
• "Too many requests", rate limit, or throttled errors
• "Bandwidth limit exceeded"
• "Your account is locked" or "temporarily disabled"
• "Server is temporarily unavailable" or capacity issues
• Still need help?

🛠️ General troubleshooting steps

Try these steps first. They resolve most authentication problems.

1. Check your credentials. Make sure your email address and password are entered correctly. Even a single typo or trailing space can 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 your 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 for provider-specific steps.

📧 Provider-specific fixes

Gmail / Google Workspace

• Make sure OAuth2 is selected as the authentication method.
• Google no longer supports Username & Password sign-in 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

• Use OAuth2 as the authentication method. Personal Microsoft accounts require it.
• Make sure IMAP is turned on: Outlook settings → Mail → Sync email → Let devices and apps use IMAP.
• If you see User is authenticated but not connected, IMAP is disabled for your account. Enable it as above, then re-add the account.

Microsoft 365 / Exchange Online

• 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. See Microsoft 365 SMTP authentication problems.
• For the best experience, we recommend using the Exchange protocol with Mailbird Premium instead of IMAP for Microsoft 365 accounts.

Yahoo / AOL

• Try OAuth2 first.
• If OAuth2 fails, generate an app password and use it with Username & Password authentication. Do not use 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 / iCloud email. You can find it in macOS System Settings, iCloud for Windows, or iCloud Mail Preferences.

Zoho Mail

• Personal accounts: use imap.zoho.com as the IMAP server.
• Business accounts: use imappro.zoho.com as the IMAP server.
• If 2FA is enabled, create an app-specific password.

BT Internet

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

⏱️ "Too many requests", rate limit, or throttled errors

The server is telling Mailbird to slow down. This usually happens when there have been too many login attempts or sync requests in a short time.

• Wait 15-30 minutes before trying again. Most providers lift rate limits automatically.
• Reduce simultaneous connections. If you access this account from multiple devices, such as a phone, laptop, and webmail, 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 incorrect 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 because of suspicious activity or too many failed logins. You must unlock it through your provider's website.

1. Sign in to your provider's web interface, such as outlook.live.com or gmail.com.
2. Look for a security challenge, unlock link, or CAPTCHA prompt.
3. Complete any verification steps your provider asks for.
4. Once the account is unlocked, wait a few minutes, then try adding it in Mailbird again.

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

⚠️ "Server is temporarily unavailable" or capacity issues

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

• Check your provider's status page, such as Google Workspace Status or Microsoft 365 Status.
• Wait 10-15 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, such as Gmail, Outlook.com, or company Microsoft 365
• The exact error message shown in Mailbird
• Whether you're using OAuth2 or Username & Password authentication
• A screenshot of the error, if possible

Our Customer Happiness Team will be happy to help.