windows smtp service
managed from the IIS 6.0 manager console
if .eml files are stuck in the c:\inetpub\mailroot\queue folder, a SMTP service restart can help force their delivery. apparently, new items can be placed directly in the pickup folder (verified – 7/11/2013).
update/correction:
when problem emails (undeliverables) are stuck in the queue then even a SMTP service restart won’t get rid of them. you’ll have to wait until the messages are expired and dropped (these settings are configurable). you could also stop the service and manually remove the problem emails and then restart the service. also anytime you actually see items in the queue that indicates a problem…
another update 7/11/2013:
you can sometimes fix mail marked as bad if you know what the exact problem is. for instance, try renaming the sender as From: <user@mydomain.com> or change the delimiters in the To: section from semicolons to commas, etc. then rename the .bad file to .eml and place it in the pickup folder to see if it sends.
the NCSA common log file format seems to provide more verbose information than the W3C format.
how to quickly send a test message:
telnet to smtp server port 25
helo me
mail from:test@test.com
rcpt to:myemail@domain.com
Data
Subject:Test
Testing
.
quit
source:
http://support.microsoft.com/kb/323350
further troubleshooting:
there is a microsoft utility called SMTPDiag that i have not tried yet
http://www.microsoft.com/en-us/download/details.aspx?id=11393