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Mac Mail App Cannot Connect — Email Account Connection and Authentication Errors

Warningapplication

Overview

Fix Mac Mail app connection failures for Gmail, Outlook, Yahoo, and IMAP/POP accounts due to authentication changes, app passwords, and SSL configuration.

Key Details

  • Mail app uses Internet Accounts framework to manage email connections
  • Google, Microsoft, and Yahoo now require OAuth2 authentication instead of plain passwords
  • App-specific passwords are needed for accounts with two-factor authentication
  • SSL/TLS settings must match the email provider's requirements for secure connections
  • Mail may show 'Cannot connect to account' or prompt for password repeatedly

Common Causes

  • Email provider requires OAuth2 authentication but Mail is using legacy password auth
  • Two-factor authentication enabled on the email account without generating an app password
  • Incorrect IMAP/SMTP server settings, ports, or SSL/TLS configuration
  • App-specific password expired or revoked on the email provider's side

Steps

  1. 1Remove and re-add the account: System Settings > Internet Accounts > select account > remove > add again
  2. 2For Gmail: remove from Internet Accounts, add as Google account (Mail will use OAuth2 automatically)
  3. 3For accounts with 2FA: generate an app-specific password from the email provider's security settings
  4. 4Check IMAP settings: Mail > Settings > Accounts > Account Information > verify server settings
  5. 5For manual setup: IMAP port 993 (SSL), SMTP port 587 (STARTTLS) or 465 (SSL) for most providers

Tags

mailemailimapauthenticationoauth

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Frequently Asked Questions

Your email provider likely requires OAuth2 authentication. Remove the account from System Settings > Internet Accounts and re-add it — Mail will use the correct modern authentication method.