I recently worked with a customer that had a “working” GALSync solution and wanted to able to share calendars between two forests.  The customer noted, the users in the target domain were being created as “Mail Contacts.”

Upon further discussion with the customer we discovered that in Forest A calendar sharing was working.  In Domain B, they were getting an error that Calendar Sharing was not available for the contact.

As we investigated it came to light that the GALSync solution was created in an Exchange 2010 environment and calendar sharing was working very well.

They acquired a company that had their own AD environment and an Exchange 2003 environment.  GALSync was configured for the acquired domain, Domain B, and was creating mail contacts without error.  Meanwhile the old Exchange 2003 Environment was upgraded to Exchange 2010.  When they tried to enable calendar sharing in Domain B for users in Domain A, they got an error that calendar sharing was not available for users from that domain.

We noticed that in Domain B, the users were created as “Mail Contacts.”  In domain A, they were being created as “Cross-forest Mail Contacts.”

After comparing the two agents using the MIIS 2003 Resource Kit tool “MA Configuration Viewer we saw that the upgraded 2010 Exchange Environment GALSync MAs were missing an attribute that the working Exchange 2010 MAs had.

By looking at the attribute flows, I noticed that the agents configured for Domain A were flowing an attribute called:

  • msExchRecipientDisplayType=   –1073741818
  • msExchRecipientTypeDetails =   32768

After modifying the acquired domains GALSync MA to include the above attributes and running through the following Run Profiles:

  1. Delta Import on each Forest A MA
  2. Delta Sync on each Forest A MA
  3. Export on the aquired Forest B MA
  4. Confirming Import on the Forest B MA

the new and existing mail contacts were either updated or created as Cross-Forest Mail Contacts

Once the correct attribute flows were configured on the Forest B MA, the users in Forest B were able to grant the ability to share calendars with users in Forest A

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