Hi,

I'm a little bit at a loss with the following and I'm not sure if there is a simple solution.

I have 2 organisations who wish to collaborate. Both these organisations run their own Exchange environments. One Exch 2013 and the other Exch 2010 in their own separate domains both are enterprise installations.

They need to be able to share/manage each other's calendars...

Any ideas?

Follow this

https://technet.microsoft.com/en-us/library/jj657473(v=exchg.150).aspx

Thanks, but I've seen this one already and doesn't provide full access permissions (modify) to each others mailbox as far as I can see.

I need people in each domain to be able to modify and create calendar entries for people in the opposite domain.

Have you taken a look here: http://www.msexchange.org/articles-tutorials/exchange-server-2010/migration-deployment/deep-dive-into-rich-coexistence-between-exchange-forests-part15.html ?

Thanks. 

Hi,

Great advice from above.

We need establish a forest trust between the forests first, then establish cross-forest availability, it provides users availability data between exchange organizations. The important point, we must deploy GALSync to represent mailbox users in the remote forest as MEU objects in the local forest, therefore we can configure cross forest delegate, as well as share calendar.

More details about Exchange Server 2010 Cross Forest Delegation, for your reference: http://blogs.technet.com/b/neiljohn/archive/2011/10/12/exchange-server-2010-cross-forest-delegation.aspx