Thanks to Vinod for the well presented answer.
I got the same error as Mick Byrne when I followed the steps above. Turning it back to All Unassigned sorted it but I had to tweak a few other things as well:
- Add the user my site was running under to the users on the Security Tab in SMTP Virtual Server.
- Changed the value in the mailSettings > network > host attribute in my web.config to the specific server IP (for example 192.168.100.120) as opposed to localhost (which was pointing at 127.0.0.1 in the hosts file).
Hope this saves someone a few mins of messing about.
