SHORT ANSWER: contact sales for an updated licnese file because of the known bug 56939
Bug 56939 – When upgraded to ZCS 7, MAPIConnectorAccountsLimit is set to 0 in license file.
On page 10 in the NE of zimbra administration documention which can be located at
http://files.zimbra.com/website/docs...se%20Notes.pdf, states that "When upgrading to ZCS 7.0.0 or later, the way in which ZCO and Archiving licensing is enforced has changed in the server. Older licenses may have MAPIConnectorAccountsLimit set to 0 or ArchivingAccountsLimit missing in the license, please contact sales for an updated licnese file prior to upgrading if you have licensed either of these features and your current license doesn't properly reflect the correct number. Use zmlicense -p to view your license information"