OAuth2 sign-in failed in Mailbird
If Mailbird opens your browser during account setup but the sign-in does not finish successfully, the issue is usually with the browser-based OAuth2 flow rather than with Mailbird itself. This can happen if the browser window is closed too early, the wrong account is selected, cookies are blocked, or the network drops during the sign-in process.
This article is the standard troubleshooting guide for generic OAuth2 setup errors, including cancelled, timed-out, exchange-failed, and connection-interrupted sign-ins.
What to check first
- Start the setup again from the beginning
Close the failed setup flow in both Mailbird and your browser, then launch a fresh attempt. - Keep the browser window open until Mailbird finishes
Do not close the provider page immediately after signing in. Wait until the browser redirects back and Mailbird confirms the connection. - Sign in with the correct email account
If you have several Google, Microsoft, or other provider accounts signed in at once, make sure you select the exact account you are trying to add. - Use your default browser
OAuth2 works best in your system default browser. If you recently changed browsers, switch back to a standard browser such as Chrome, Edge, Safari, or Firefox and retry.
Fixes for common OAuth2 failures
- Browser closed too early: Run the setup again and leave the browser page open until Mailbird finishes.
- Timed out: Restart the setup and complete the sign-in flow without leaving the browser idle for too long.
- Wrong account selected: Sign out of other accounts in the browser first, or deliberately choose the correct account when prompted.
- Cookies or cache issue: Clear your browser cache and cookies for the provider, then try again.
- Browser restriction or extension interference: Temporarily disable ad blockers, privacy extensions, script blockers, or security tools that can interrupt sign-in redirects.
- Network interruption: Make sure your internet connection is stable. If needed, switch networks and retry.
- Provider session problem: Sign in to the provider website manually in the browser first, then return to Mailbird and start the setup again.
Should you use a private or incognito window?
Usually, the default browser session is best. If the standard flow repeatedly fails because of cached sessions or the wrong signed-in account, a private or incognito window can help isolate the login attempt. Use it only as a troubleshooting step, not as the default recommendation.
Provider-specific notes
- Gmail: OAuth2 is the preferred connection method. If Gmail sign-in keeps failing, review our Gmail authorization troubleshooting article.
- Microsoft 365 / Outlook: If Microsoft sign-in is involved, also review Microsoft OAuth 2.0 support.
When to try again later
If the provider login page itself is slow, unavailable, or returns a temporary error in your browser, wait a little and retry later. OAuth2 setup can fail if the provider is having a temporary authentication issue.
Still stuck?
If the same OAuth2 flow fails every time, contact support with the provider name, the exact error wording, and the step where the process breaks: browser opens, login page appears, redirect fails, or Mailbird rejects the completed sign-in.