Method 1:  Meeting Invitation

1. Open the shared calendar of the Resource Account in Outlook desktop app
2. Create a meeting on that calendar
3. Invite desired recipients
1. If large number of recipients untoggle Request Responses (under the Attendees toolbar)
4. Everyone will receive a calendar invitation from “[You] sent on behalf Resource Account”

Method 2:  Announcement

1. Add the shared mailbox to your Outlook desktop inbox if not already mounted.
2. Open the shared calendar of the Resource Account in Outlook desktop app
3. Create an appointment on the Resource Calendar
4. While still editing the appointment, under Actions click Forward as iCalendar
5. On the From box in the generated email, toggle from [You] to the Resource Account
6. Send the email
7. Everyone will receive an email with the attached ics file.  When opened, it will allow them to save the meeting/event notice.