Selecting MAPI from Address button in Send Mail action results in error: Could not open address book.
The flag (Contents field) for SimpleMAPI integration is set to '1' in the HEATINI table where INISection = SysMail and INIEntry = SimpleMAPI.
Run the following SQL statement:
SET Contents = '0'
WHERE INISection = 'SysMail'
AND INIEntry = 'SimpleMAPI'