How do I stop email reminder from iCal?
For Mac OS X Mountain Lion  10.8.0:


Click on the "Calendars" button on the main window to show the sidebar of calendars.
Right mouse click on the calendar you want to ignore alerts from &amp; choose "Get Info"
Check ON "Ignore Alerts" &amp; click "OK"


Seems as thought you don't have to globally set this preference, you can now selectively choose which calendars have alerts or not, through iCal.