How to Check SMTP Logs in Windows Server (IIS)?

You may face an issue sending emails from your website (PHP or ASP.NET) using the local server SMTP service. In this case, you must check the SMTP logs of the Internet Information Service (IIS). 

Please refer to the following steps to check the SMTP logs in the Windows Server (IIS) – 

Enable SMTP Logs

1. Log in to your server. 

2. Go to Start > Administrative tools.

3. Click on Internet Information Service (IIS) 6.0 Manager.

4. Expand your hostname at IIS 6; it will show you SMTP Virtual Server #1.

5. Right-click on SMTP Virtual Server and click on Properties.

6. Click on Enable logging and then click on the Properties button. 

7. At the logging properties, click on the Advanced tab, check all the boxes, then click on the OK button. 

Check SMTP Logs

Once the SMTP logs are enabled, we can find all the logs at the location mentioned below – 

C:\WINDOWS\system32\LogFiles\SMTPSVC1

Understand the SMTP Log

If you find the status code '250', it means OK.
Here is the understanding of SMTP status codes.