Have you looked at Domain Admin... Shared Resources... Calendar?

Works for web interface but not for phones, EAS, and desktops, MAPI, running Outlook. Maybe there's a way to map or sync but I haven't figured it out.

IMAP not MAPI

For Outlook / IMAP, / POP use CalDavSynchronizer. (third party but free)

For ActiveSync, it works after the Calendar is attached in Webmail - no other comfigutation needed

For Iphone / EAS, use a CalDav connection

We are using all of these successfully.

Thank you Douglas. I did have it setup as shared calendar and attached but maybe I need to reset the Outlook profile because it is not displaying on their phones. With this information I will get to troubleshoot again and see if I can resolve the issue, will let you know. Again thanks a bunch. 

Tried the CalDavSynchronizer and had some strange results but still not able to see the shared calendar on the desktop. The personal calendar is available with this setup but every time you sync appointments get duplicated using it with Outlook 2010. I will get a chance to try it with 2013 this after noon. Do I have to disable or somehow remove the personal calendar to see the shared one?

Thanks you Douglas, I am just getting back to this problems and will give it a try this morning. We are using Outlook 2013 but should work the same if it is working for you. Will let you know in a couple hours.

I can't say anything good about Outlook 2013.   If you have problems, I would recommend an upgrade to 2016 or a downgrade to 2010.

Douglas, I had a computer with Office 2010 in the office so tried your instructions I was able to get it working so now I need to see if I can get it working on Office 2013 and also get it to the iphones. At lease I know it works somehow and that is reassuring. I will keep you posted on the progress.

PS: The final three items in step 13 were default values.

Okay, Company calendar is working with Outlook 2013 and the CalDavSyncronizer. No strange sync problem as I appeared to have before. Problem seem to be an older version of CalDavSyncronizer. Also iphones are getting the Company calendar. Everything is working as advertised. Thanks again for all the help Douglas.

Douglas, I am trying to see if CalDavSyncronizer can be used with smartermail to also do contacts. Have you tried this and do you know how to determine the url to the shared folder?

We have just discovered that the SharePoint Lists protocol is being deprecated by SmarterMail because it has been deprecated by Microsoft.    We stumbled on this after discovering that most of our users who had configured AddToOutlook for Contact synchronization were having large numbers of conflicts, which we found in 

"(all folders icon)... SharePoint Lists... Sync Issues".   The interim workaround is to delete all conflicts or delete the sharepoint list and recreate it using AddToOutlook.

The Contact URL is only visible in the newer versions of SmarterMail.  In the versions that have the patch, it is obtained in the same way as the Calendar URL, from the properties window.

We have not upgraded yet, but now I have incentive to do so soon.   I am waiting for one more patch cycle to get the latest fixes for IMAP.   Consequently, I have not tried CalCavSync with My Contacts, but I fully expect that it will work.

Thanks again, I was also slow on updating but will do it now. I am so grateful for the help on this.

After three days the update seems to be no problems at all. Shared contacts for admin and it is working as advertised. Thanks again to Douglas.