diff --git a/lib/calendarClient.ts b/lib/calendarClient.ts
index fe1e7111b3..855ed6ea7b 100644
--- a/lib/calendarClient.ts
+++ b/lib/calendarClient.ts
@@ -135,7 +135,10 @@ const MicrosoftOffice365Calendar = (credential): CalendarApiAdapter => {
                 'Content-Type': 'application/json',
             },
             body: JSON.stringify(translateEvent(event))
-        }).then(handleErrors))
+        }).then(handleErrors).then( (responseBody) => ({
+            ...responseBody,
+            disableConfirmationEmail: true,
+        })))
     }
 };
 
@@ -228,14 +231,17 @@ const getBusyTimes = (withCredentials, dateFrom, dateTo) => Promise.all(
     (results) => results.reduce( (acc, availability) => acc.concat(availability), [])
 );
 
-const createEvent = (credential, calEvent: CalendarEvent) => {
-    if (credential) {
-        return calendars([credential])[0].createEvent(calEvent);
-    }
-    // send email if no Calendar integration is found for now.
+const createEvent = (credential, calEvent: CalendarEvent): Promise<any> => {
+
     createNewEventEmail(
       calEvent,
     );
+
+    if (credential) {
+        return calendars([credential])[0].createEvent(calEvent);
+    }
+
+    return Promise.resolve({});
 };
 
 export { getBusyTimes, createEvent, CalendarEvent };
diff --git a/pages/api/book/[user].ts b/pages/api/book/[user].ts
index 9d55b1575f..7abeadf1c8 100644
--- a/pages/api/book/[user].ts
+++ b/pages/api/book/[user].ts
@@ -31,12 +31,13 @@ export default async function handler(req: NextApiRequest, res: NextApiResponse)
         ]
     };
 
-    // TODO: for now, first integration created; primary = obvious todo; ability to change primary.
     const result = await createEvent(currentUser.credentials[0], evt);
 
-    createConfirmBookedEmail(
-      evt
-    );
+    if (!result.disableConfirmationEmail) {
+        createConfirmBookedEmail(
+          evt
+        );
+    }
 
     res.status(200).json(result);
 }