For anyone not using it, the great thing about Little Snitch is being able to set just the precise port numbers and remote hosts you want a given app to access

For anyone not using it, the great thing about Little Snitch is being able to set just the precise port numbers and remote hosts you want a given app to access while blocking everything else, rendering plug-ins like MailTrackerBlocker unnecessary. You can also set profiles for different networks, and even have them switch automatically: https://help.obdev.at/littlesnitch/adv-profiles https://help.obdev.at/littlesnitch/adv-profiles .