In order to enable transport logging in outlook one need to perform below mentioned steps:
1. Open outlook -> Go to Tools menu and click Options.
2. Click the Other tab.
3. Click the Advanced Options button.
4. Click to select the Enable mail logging (troubleshooting) check box.
5. Click OK to save the setting, and then return to the main Options screen.
6. Click OK.
7. Quit and restart Outlook.