a person would scroll to the bottom of the page and hit "Submit" The problem is that the message will not send if the default "Attach a signature (signatures can be altered via the UCP)" box is checked blue.
This box must be unchecked for the message to send.
Another option is to make a signature. This can be done by clicking the "Profile" and then "Edit signature".
Add your name, or handle, or tag that can be sent with your private messages. Scroll down and hit "Submit" and return to the Private messages tab.
Once this step is completed the default setting for attach signature will add your tag and messages will send.
Without removing the check from the "Attach a signature (signatures can be altered via the UCP)" or adding a signature all messages that you try to send are permanently lost and have to be retyped.

Spike188 aka Eugene with an E and Eugen