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

11. Email > 05. SMTP & Outlook Configuration
How To Check SMTP Logs in Windows Server (IIS)?
Problem
Sometimes you cannot send out emails with Microsoft local SMTP Service (127.0.0.1) in your ASP.NET codes.
Solution
You can check the SMTP logs to see what happens. Please follow these steps to set up and check SMTP log files.
a. Enable SMTP Logs
Open Start > Server Manager > Tools > Internet Information Service (IIS) 6.0 Manager. Right-click "SMTP Virtual Server" and choose "Properties". Check "Enable logging".
Click "Properties ..." to check all options.

b. Check SMTP Logs

You can check the SMTP log files at C:\WINDOWS\system32\LogFiles\SMTPSVC1.

c. Understand SMTP logs

You can open the log file and check the email logs. The most important field is the status code. "250" means ok.
Here is the meaning of SMTP status codes.
Status Code
Description
211
System status, or system help reply
214
Help message
220
Service ready 
221
Service closing transmission channel 
250
Requested mail action okay, completed 
251
User not local; will forward to 
354
Start mail input; end with "."
421
Service not available, closing transmission channel
450
Requested mail action not taken: mailbox unavailable
451
Requested action aborted: local error in processing
452
Requested action not taken: insufficient system storage
500
Syntax error, command unrecognized
501
Syntax error in parameters or arguments
502
Command not implemented
503
Bad sequence of commands
504
Command parameter not implemented
550
Requested action not taken: mailbox unavailable
551
User not local; please try <....>
552
Requested mail action aborted: exceeded storage allocation
553
Requested action not taken: mailbox name not allowed
554
Transaction failed
 
Article ID: 498, , Modified: February 10, 2021 at 3:55 AM

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