How can I send email automatically when activity is updated in Zoho CRM

How can I send email automatically when activity is updated in Zoho CRM

I have a custom function that create a meeting and send meeting notification to the participants when a specific stage is reached in my custom module. 

When I update the stage in my custom module, the title of the meeting and its contents gets changed. However the Calendar invitation that the participant received the first time is not getting updated so in his Mail calendar he stills sees the content of the invitation which was generated at the beginning. 

how can I force the calendar invite to be updated with the content of the updated meeting ? 

Thanks

here's my script 

(my custom Module is called "Trainings")

TrainingDetails = zoho.crm.getRecordById("Trainings",training_id);

startdate = ifnull(TrainingDetails.get("Start_Date"),"").toString();

enddate = ifnull(TrainingDetails.get("End_Date"),"").toString();

meeting = ifnull(TrainingDetails.get("Meeting_ID"),"");
//get XXXX Status
status = ifnull(TrainingDetails.get("Status_XXX"),"");
eventmap = Map();
//No Meeting invite Created
if(isNull(meeting))
{
info "No Meeting Yet, let's create one";
if(status = "No Commitment")
{
info "Create a meeting which is not confirmed yet";
eventmap.put("Event_Title","Blocker - Not Confirmed - Training - " + ifnull(TrainingDetails.get("Course"),""));
}
else
{
info "Meeting is confirmed, we can update the trainer's calendar";
eventmap.put("Event_Title","Training - Confirmed " + ifnull(TrainingDetails.get("Course"),""));
}
}
else
{
if(status = "No Commitment")
{
eventmap.put("Event_Title","Blocker - Not Confirmed - Training - " + ifnull(TrainingDetails.get("Course"),""));
}
else if(status = "Cancelled")
{
eventmap.put("Event_Title","Cancellation - Training" + ifnull(TrainingDetails.get("Course"),""));
}
else
{
eventmap.put("Event_Title","Training - Confirmed " + ifnull(TrainingDetails.get("Course"),""));
}
}


eventmap.put("Owner",ifnull(TrainingDetails.get("Owner"),"").get("id"));

partList = List();
partMap = Map();
partMap.put("type","user");
partMap.put("participant",TrainingDetails.get("Trainer").get("id").toLong());

partList.add(partMap);
eventmap.put("Participants",partList);
eventmap.put("What_Id",training_id);
eventmap.put("$se_module","Trainings");
eventmap.put("$calendar_booking_event",TRUE);
eventmap.put("Description","New " + ifnull(TrainingDetails.get("Language"),"") + " training for XXX : here are the course(s) " + ifnull(TrainingDetails.get("Course"),"") + " Class ID:" + ifnull(TrainingDetails.get("Class_ID"),"") + " https://crm.zoho.eu/crm/orgABCDE/tab/CustomModule4/" + training_id);
eventmap.put("send_notification",true);
eventmap.put("Venue",ifnull(TrainingDetails.get("Type"),"") + " " + ifnull(TrainingDetails.get("City"),""));
//eventmap.put("$meeting_details",ifnull(TrainingDetails.get("Notes"),""));
eventmap.put("Start_DateTime",startdate);
eventmap.put("End_DateTime",enddate);
eventmap.put("id",ifnull(TrainingDetails.get("Training_Number"),""));
info eventmap;
if(isNull(meeting))
{
info "No Meeting yet, let's create it with all the data";
Event = zoho.crm.createRecord("Events",eventmap);
info Event;
meeting_id = Event.get("id");
info meeting_id;
mp = Map();
mp.put("Meeting_ID",meeting_id);
updatetraining = zoho.crm.updateRecord("Trainings",training_id,mp);
}
else if(status = "Cancelled")
{
//Training cancelled, let's update the Event with new cancellation information and send update to the participant's calendar
info "cancelled";
Event = zoho.crm.updateRecord("Events",TrainingDetails.get("Meeting_ID"),eventmap);
}
else
{
//Training is still going so let's update the Event with new information and send update to the participant's calendar
Event = zoho.crm.updateRecord("Events",TrainingDetails.get("Meeting_ID"),eventmap);
}