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

# Configuring SMTP Authentication in Outlook (v.2016)

If you get the following error message in your Outlook:

The **“Error 503: Valid RCPT command must precede DATA”** happens when sending email. It’s telling you that your SMTP (outgoing mail) connection was not properly authenticated by your email server.

Most likely reason for this problem is that SMTP Authentication is not configured in your email client. To configure it in Outlook 2016, please follow the steps below:

1. Open Outlook 2016.

2. Open the File menu and select **Account Settings –> Account Settings**.

![](https://tutorials.my-virtual-panel.com/outlook_auth/2_Outlook_2016_smtpauth.png)

3. In the Account Settings window, select the email account you wish to set up and click **Change**

![](https://tutorials.my-virtual-panel.com/outlook_auth/3_Outlook_2016_smtpauth.png)

4. In the Change Account window, click **More Settings** 

![](https://tutorials.my-virtual-panel.com/outlook_auth/4_Outlook_2016_smtpauth.png)

5. From the More Settings window, select the **Outgoing Server** tab.

6. Check My outgoing server (SMTP) **requires authentication**.

![](https://tutorials.my-virtual-panel.com/outlook_auth/6_Outlook_2016_smtpauth.png)

7. Select **Use same settings** as my incoming mail server.

8. Open the **Advanced tab**.

9. In the Advanced tab, set the **Outgoing server (SMTP) port to 465**. In the **Use the following type of encryption** drop-down, select **SSL**.

10. Click OK.

![](https://tutorials.my-virtual-panel.com/outlook_auth/10_Outlook_2016_smtpauth.png)

11. On the Internet **E-Mail Settings** window, click **Next**.

12. Click **Finish**.

![](https://tutorials.my-virtual-panel.com/outlook_auth/12_Outlook_2016_smtpauth.png)