> This page is for Docs.

> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://zuora.ferndocs.com/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://zuora.ferndocs.com/_mcp/server.

# Common error messages and actions for external SMTP server

> Use this reference to troubleshoot errors when configuring an external SMTP server.

Use this reference to troubleshoot errors when configuring an external SMTP server.

##

The following table lists the common error messages and recommended actions for configuring external SMTP server.

<table>
  <tr>
    <th>
      Error Message
    </th>

    <th>
      Recommended Action
    </th>
  </tr>

  <tr>
    <td>
      Unknown SMTP host
    </td>

    <td>
      Check that the SMTP Server Name is correct.
    </td>
  </tr>

  <tr>
    <td>
      Could not connect to SMTP host
    </td>

    Check that the SMTP Port is correct. If the port is correct, the SMTP server might be experiencing a temporary issue. Wait a few minutes and try again.
  </tr>

  <tr>
    <td>
      Connect timed out
    </td>
  </tr>

  <tr>
    <td>
      Authentication failed: Bad username / password
    </td>

    <td>
      Check whether your username and password are correct.
    </td>
  </tr>

  <tr>
    <td>
      Authentication failed
    </td>

    <td>
      Check whether your username and password, or OAuth 2.0 provider configuration are correct.
    </td>
  </tr>

  <tr>
    <td>
      Authentication required
    </td>

    <td>
      Check if you have configured the **Authentication** field.
    </td>
  </tr>

  <tr>
    <td>
      Read timed out
    </td>

    Check that you have entered the correct values for the following fields:

    * SMTP SocketFactory Port
    * SMTP SocketFactory Class
    * SMTP SocketFactory Fallback
  </tr>

  <tr>
    <td>
      Could not convert socket to TLS
    </td>
  </tr>
</table>