This tutorial will show you how to sync Webmail Calendar with Outlook 2013.
Without adding the email account itself to the Outlook Desktop Client Software, you can sync a Webmail Calendar to multiple instances of Outlook.
Step 1: In Webmail, go into Calendar.
Step 2: From the Actions menu, select Add to Outlook.
Step 3: Click OK.
Step 4: Click Open link.
Step 5: Click Advanced...
Step 6: Give this calendar a name, then click OK.
Step 7: Click Yes.
Step 8: You will now see your Webmail Calendar folder.