---
title: "Connection and authentication errors"
description: "Fix rejected credentials, an expired OAuth connection, or a timeout when BooleanSMTP contacts a provider."
image: "https://booleansmtp.com/docs/og.png"
---

> Documentation Index
> Fetch the complete documentation index at: https://booleansmtp.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# 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](/docs/mailers/)
- [Send a test email](/docs/getting-started/send-a-test-email/)
- [Troubleshooting overview](/docs/troubleshooting/)

Source: https://booleansmtp.com/docs/troubleshooting/connection-errors/index.mdx