I introduced a new Exchange 2013 server into our organization and migrated all of our mailboxes from Exchange 2010 over the weekend. Mail flow is working fine, Outlook 2007 is connecting, Active Sync on iphones and Outlook Web is all working fine. However I am having a problem with Lync 2013 IM conversation history posting to Outlook / Exchange after the migration. I don't have any error messages that I can see in the Lync 2013 desktop client or on either server event log. I am using a self signed cert for the Lync 2013 product and a GoDaddy cert for the Exchange 2013 product. I confirmed that my auto discover URL is correct and that all my internal and external virtual directories are configured properly. Some advice would be kindly appreciated.