Yes! Set up a calendar event to send an email reminder and all members of your group will receive notification in advance of the event. You can set up two reminders, and these can be triggered anywhere from two weeks to 5 minutes before the event.

Note: If a user’s messages are moderated, then calendar reminders will not work for the events created by that user (even if they have set reminders when creating the event). If you are a moderator, you can learn more about how to change a user’s moderation settings here: http://help.yahoo.com/l/us/yahoo/groups/original/ownmod/inviting/inviting-10.html