Add a notice

Click on +New Notice - button below any notices.

Click on Notice Type - Welcome - to see the list of notices available.

Click to choose the notice you want to create or edit.

Fill in the information on the form.

As a special case, the Guidelines can be sent on join and/or monthly, in addition to appearing in the left column.

Click on Add Notice to save the notice.

Activate, deactivate, edit or delete notices

New notices you create are automatically activated (default) except for type Invite. However you may want to change that.

In Admin, Settings, the button for Member Notices

Make sure that only the ones you want are activated.

Click on a hyperlinked title.

You will see

Active Message - with a tick box and the explanation line: Use this message.

You can also edit or delete a Notice you don't want.

Don't forget to click on Update Notice.

Banned-Member: Message sent when someone is banned from your group
Direct-Add: Message sent when a person is directly added to your group. NOTE: You have to manually select which one to include when you do a direct add.
Group-Guidelines: Group guidelines (see below for extra options)
Goodbye: Message sent when someone leaves your group
Invite: Message sent when an invite is sent. NOTE: You have to manually select which one to include when you send an invitation.
Note-To-Member: Message sent to a member. You can send via the member listing in Admin. Bottom of the page. Choose which message, if you have more than one. This note type does not have the blue Active button.
Locked-Group: Message returned when someone emails the group when it is locked.
Monthly-Reminder: Message sent to the group every month. You can't actually send the contents of a file so you have to include the text wanted or a link to a file.
Pending-Subscription: Message sent when someone applies to join your group
Rejected-Message: Message sent when a message is rejected
Rejected-Subscription: Message sent when a pending subscription is rejected
Removed-Member: Message sent when a member is removed from your group
Welcome: Message sent when someone joins your group

The "Group Guidelines" type of member notice operates differently and has the following features and options:

When you set a "Group Guidelines" notice, a new tab appears on the left called "Guidelines" with the notice's content in it
You can make the "Group Guidelines" notice visible only to members (this relates to the Guidelines tab on the left)
You can set two different subject lines
You can set the "Group Guidelines" notice to be sent when people join as members
You can set the "Group Guidelines" notice to be be sent every month
- If you set it to be sent every month, you can choose to send it as a special notice, to ensure that members who are subscribed as "Special Notices Only" will also receive it
You can only set one "Group Guidelines" member notice at a time (it will disappear from the dropdown list when one such notice has been created)

Also:

Since you can use hashtags in the subject line, you can the hashtag functionality to do certain things, e.g.:
- delete the previous guidelines post from the group automatically by setting the hashtag's duration as "one month".
- set the hashtag to "locked" so that no-one can reply to the guidelines post.
The guidelines can be sent manually by a moderator to a group member at any time, in case the member needs a review of the guidelines
Examples : https://groups.io/g/GroupManagersForum/wiki/Group-Rules