See also: https://groups.io/g/GroupManagersForum/message/3749
Here's what it looks like on receipt:
From: "email@example.com Calendar" <firstname.lastname@example.org>
Subject: [shalstest] The event name you enter - Sun, 2/11/18 #cal-notice
Date: Sun, 11 Feb 2018 00:00:02 -0800
The event name you enter
Sunday, 11 February 2018
This event serves as an example of using an event to post a scheduled message to one's group. I've set it to two weeks, matching one of the choices available in Yahoo Groups (the other choice being monthly). In a Groups.io event the scheduling is far more flexible.
The schedule, the event name, and the descriptive text are under your control. The rest of the message is boilerplate you can't change.