Hi @vicecaz 

I am assuming you would want to be notified when the events are created? 
This would be a tricky integration to set up in Zapier as there are no triggers that can watch for spacing between two events. Likely, you will need a complicated system that triggers from a New Event added to your calendar and with some database that can be referenced for other events. 

It would be difficult to do with a formula but a script could help. Feel free to shoot us a direct message if you want to hire out for this. Otherwise, I will help as much as I can here

@vicecaz 

You may be able to have some luck using the Find Event action with Google Calendar and a couple of formatters & filters. 

To get the wheels moving here is an example idea that checks if there is an event in front of the new event.

• Trigger: New Event in Google Calendar (you could also do New or Updated Event)
• Step 2: Formatter action to subtract 16 minutes from the Start Time of the event
• Step 3: Find Event in Google Calendar. 
  • This search needs to be as nondescript as possible. I would search for a period and filter the time to the time from step 2 as the start time and use the end time of my event. See the screenshot below. Any event should match a period because there is one in the timestamp of any event.
  • You could also add a second formatter to add 16 minutes to the end time and use that as the end time to search for events. You are essentially giving Zapier a window to look for events in 
• Step 4: Filter to make sure the returned event is not the same event as the trigger.
  • Check to make sure the id of the event returned in the search step is not the same as the id of the event that triggered Zapier. 
• Step 5: Send email