Connection and authentication errors

“Authentication failed” in the logs

The provider rejected the credentials or a security setting blocked the connection.

1. Recheck the connection’s credential fields and re-enter any value you suspect is wrong.
2. For Google Workspace or Microsoft Outlook, follow the OAuth steps below.
3. For SMTP, check whether the provider requires an app-specific password instead of your account password.

An OAuth connection stopped sending

The provider may have revoked access after a password change, removed app permission, or security review. BooleanSMTP checks token validity before sending and refreshes a token when needed.

1. Open the connection and click Authorize (or Reconnect account if it has connected before).
2. Send a test email from that connection to confirm it works again.

Connection timeout

Your host or a firewall between it and the provider may be blocking the connection.

1. Confirm your host allows outbound connections on the port the connection uses.
2. Click Verify credentials on the connection to test it again.
3. Ask your hosting provider whether it restricts outbound SMTP or the port your provider needs.

Next steps

• Set up a mailer
• Send a test email
• Troubleshooting overview