To protect our users from spam and other unsolicited commercial messages, Facebook has imposed stringent guidelines that flag when a user repeatedly sends or posts the same message, even if you were simply trying to organize a group or event.
Facebook has several recommended alternatives that can ensure these situations don’t arise again. If you were trying to organize an event and were sending out all of the information in messages, we suggest you create a Facebook Event by going to the Events page and then clicking "Create an Event." You can then fill in all the necessary information for the event and invite all your friends using the invite feature within the event. You can also utilize the "Message All" feature, which allows you to message all guests that have RSVP’d ‘yes’ to the event.
If you were trying to promote your group by posting a link to join it in a message, on a wall, on someone's timeline, or in a discussion board, this can be construed as spam. We suggest making your friends administrators of this group so that they can invite their friends using the Invite functionality built into the group. You can do this by clicking on "Edit Group Members" and then on "make admin" next to the users’ names. Each admin can invite his/her own friends to the group.