Gmail sending automatic emails with calendar updates

Several coworkers and I have recently switched to iPhone 6's from galaxy S5's. We use a program called Sync2 to sync our outlook calendars with our phones via a gmail account. It worked perfectly on the S5, and works fine on the iPhone except that it periodically sens automatic updates from the gmail accounts used to sync the calendars to everyone on the meeting invite list. Very annoying. Anyone have any ideas how to stop this?