To verify the problem is with smtp and not with cdosys configuration...
Go to the mailroot sub directory in your inetpub directory. check out what's in the folders under mailroot. May get some clues. Also check your error logs.
To test if smtp is running properly...
Copy the following 4 lines into a .txt file:
From: emailaddress@someplace.com
To: emailaddress@someplace.com
Subject: testing
This is the test message body.
Change the email addresses to something you can check.
Copy the text file (not a shortcut) to the smtp pickup directory. On my XP machine, it's C:\Inetpub\mailroot\Pickup
Within a few seconds it should disappear from the directory and be mailed to the addresses.
Check the other directories inder mairoot to see if there are errors. If the .txt file doesn't disappear from the Pickup directory, stop and start smtp.