I understand that  your organization is seeking for a volunteer management system that enables easy scheduling, groups and shift scheduling for volunteers. Here are some great options to consider.

1. Galaxy digital's get connected: With this tool, automatic scheduling and recurring shifts are guaranteed. Volunteers can also manage their shifts, schedules and find substitutes on their personal portals.

 2. Volgistics: This tool allows for a lot of customization, recurring shifts and automatic scheduling.

 3. Outlook or Slack:These are tools that feature direct communication between members, channels, groups feature ,meetings set-up and schedule arrangements.

 4. Zapier: This tool allows you to create work flows in such a way that it can automatically assign volunteers to shifts, send them reminders and manage cancellation.

 In choosing the appropriate tools for your organization. It is important to take into consideration the financial cost, the size of your organization and the current number of volunteers. To enable you maximize and make good use of whatever tool you choose.