IIS SMTP - The server response was: 5.7.1 Unable to relay for outgoing address, Still not working

Question

I have read Mailbox unavailable. The server response was: 5.7.1 Unable to relay for abc@xyz.com and all of the answers. I have added my IP address via

Answer 1

I was able to fix this in my case by:

1. Go to Administrative Tools -> IIS 6.0 Manager
2. Right click "SMTP Virtual Server" then Click Properties
3. Select Access tab
4. Click "Relay..." in Relay Restrictions
5. Select "Only the list below"
6. Add 127.0.0.1 and my server IP to the list
7. Check Allow all computers which successfully authenticate to relay, regardless of the list above
8. Click "OK"