The full message will be available after the message has been recovered. Items within the recover utility will only show the message headers.Look below for steps to recover a deleted calendar.

If a calendar is deleted, it can only be recovered using Outlook desktop client - you cannot use Outlook on the web.All messages will be restored to your inbox regardless of which folder they were deleted from. Only messages can be restored (the folder structure cannot be restored). If a mail folder is deleted, it cannot be restored.Also, if items are purged from the Deleted Items folder, which can be done at any point, including within the 14 day window, they can no longer be recovered.

After this time elapses, items cannot be restored.

Items can only be recovered within 14 days of when they were emptied from within the Deleted Items folder.

All Office 365 accounts are not backed up.

Once this folder has been emptied, some Microsoft clients, including Outlook Web App and some desktop versions of Outlook, allow you to recover deleted items that are no longer visible in your Deleted Items folder. Depending on your settings, these messages may be periodically emptied from your Deleted Items folder. When you delete an item (email, calendar event, task, etc.), it is moved to your Deleted Items folder. The following document explains how to recover messages that have been emptied from your Deleted Items folder.

Exchange 2010 deleted items recovery