I have an Exchange and Outlook 2010 environment. Let's say our e-mail domain is domain1.com.
Recently we acquired another company and now their e-mail hosted on my Exchange 2010 server. Let's say that their e-mail domain is domain2.com. Their e-mail was formerly with Group Spark, a hosted Exchange provider. I exported their mailboxes to .pst files and then imported them in to new mailboxes on my Exchange 2010 server. When our companies were separate our users were contacts in their Outlook/GroupSpark Contacts lists. When they update meetings that were organized before thier mailboxes were on my Exchange server, they recdeive a bounceback from meeting recipients on their own domain2.com.
This doesn't happen if they delete those recipients and re-select them from the GAL before sending the update. Additionally if they try to send an e-mail to recipients on their domain it will bounce back if they fill in the To: box using auto complete or select from their (now migrated) contact list. Again no bounce back if using the GAL. I think their contacts have an identifier associated with when they were on hosted Exchange. If that's true, can I change it?