Answer
All mail sent from GMS Webmail, along with all mail generated by MML scripts is placed into the outlocalhost directory. From here it is posted to the local SMTP service.
This is done so that all settings that apply to incoming SMTP mail will also equally apply to messages generated by the webmail service. This includes all teh Juce and AV checks.
As this mail is sent from "localhost" it automatically uses the IP address 127.0.0.1, the two normally being associated with each other via an entry in the hosts file.
Localhost is a "special" hostname that always refers to the local machine.
Keywords:127.0.0.1, localhost, loopback, send, mail