diff --git a/__test__/features/Events/EventDisplay.test.tsx b/__test__/features/Events/EventDisplay.test.tsx
index a42bcd8..7502b8b 100644
--- a/__test__/features/Events/EventDisplay.test.tsx
+++ b/__test__/features/Events/EventDisplay.test.tsx
@@ -650,7 +650,7 @@ describe("Event Preview Display", () => {
 
     fireEvent.click(emailButton);
 
-    const expectedUrl = `test/mailto/?uri=mailto:john@test.com&subject=Test%20Event`;
+    const expectedUrl = `test/mailto/?uri=mailto%3Ajohn%40test.com&subject=Test%20Event`;
 
     expect(mockOpen).toHaveBeenCalledWith(expectedUrl);
   });
@@ -721,7 +721,7 @@ describe("Event Preview Display", () => {
 
     fireEvent.click(emailButton);
 
-    const expectedUrl = `test/mailto/?uri=mailto:john@test.com&subject=Meeting%20%26%20Discussion%3F%20%23Important`;
+    const expectedUrl = `test/mailto/?uri=mailto%3Ajohn%40test.com&subject=Meeting%20%26%20Discussion%3F%20%23Important`;
 
     expect(mockOpen).toHaveBeenCalledWith(expectedUrl);
   });
diff --git a/src/components/Event/utils/eventUtils.tsx b/src/components/Event/utils/eventUtils.tsx
index ab51f05..68bc988 100644
--- a/src/components/Event/utils/eventUtils.tsx
+++ b/src/components/Event/utils/eventUtils.tsx
@@ -18,7 +18,8 @@ export function renderAttendeeBadge(
   key: string,
   t: (key: string) => string,
   isFull?: boolean,
-  isOrganizer?: boolean
+  isOrganizer?: boolean,
+  caption?: string
 ) {
   const classIcon =
     a.partstat === "ACCEPTED" ? (
@@ -65,12 +66,19 @@ export function renderAttendeeBadge(
           <Avatar {...stringAvatar(a.cn || a.cal_address)} />
         </Badge>
         <Box style={{ display: "flex", flexDirection: "column", minWidth: 0 }}>
-          <Typography noWrap>{a.cn || a.cal_address}</Typography>
+          <Typography variant="body2" noWrap>
+            {a.cn || a.cal_address}
+          </Typography>
           {isOrganizer && (
             <Typography variant="caption" color="text.secondary">
               {t("event.organizer")}
             </Typography>
           )}
+          {caption && (
+            <Typography variant="caption" color="text.secondary">
+              {caption}
+            </Typography>
+          )}
         </Box>
       </Box>
     );
diff --git a/src/features/Events/EventPreview/EventPreviewActionMenu.tsx b/src/features/Events/EventPreview/EventPreviewActionMenu.tsx
index 8fb210b..ebf7523 100644
--- a/src/features/Events/EventPreview/EventPreviewActionMenu.tsx
+++ b/src/features/Events/EventPreview/EventPreviewActionMenu.tsx
@@ -36,9 +36,9 @@ export function EventPreviewActionMenu({
         <MenuItem
           onClick={() =>
             window.open(
-              `${mailSpaUrl}/mailto/?uri=mailto:${otherAttendees
-                .map((a) => a.cal_address)
-                .join(",")}&subject=${encodeURIComponent(event.title ?? "")}`
+              `${mailSpaUrl}/mailto/?uri=${encodeURIComponent(
+                `mailto:${otherAttendees.map((a) => a.cal_address).join(",")}`
+              )}&subject=${encodeURIComponent(event.title ?? "")}`
             )
           }
         >
diff --git a/src/features/Events/EventPreview/EventPreviewAttendees.tsx b/src/features/Events/EventPreview/EventPreviewAttendees.tsx
index 4da1b33..5deac66 100644
--- a/src/features/Events/EventPreview/EventPreviewAttendees.tsx
+++ b/src/features/Events/EventPreview/EventPreviewAttendees.tsx
@@ -1,3 +1,4 @@
+import { useAttendeesFreeBusy } from "@/components/Attendees/useFreeBusy";
 import { renderAttendeeBadge } from "@/components/Event/utils/eventUtils";
 import { AvatarGroup, Box, Typography } from "@linagora/twake-mui";
 import PeopleAltOutlinedIcon from "@mui/icons-material/PeopleAltOutlined";
@@ -11,6 +12,10 @@ interface EventPreviewAttendeesProps {
   attendees: userAttendee[];
   organizer: userAttendee | undefined;
   allAttendees: userAttendee[];
+  start?: string;
+  end?: string;
+  timezone?: string;
+  eventUid?: string | null;
 }
 
 const ATTENDEE_DISPLAY_LIMIT = 3;
@@ -19,6 +24,10 @@ export function EventPreviewAttendees({
   attendees,
   organizer,
   allAttendees,
+  start,
+  end,
+  timezone,
+  eventUid,
 }: EventPreviewAttendeesProps) {
   const { t } = useI18n();
   const theme = useTheme();
@@ -29,6 +38,26 @@ export function EventPreviewAttendees({
 
   const attendeePreview = makeAttendeePreview(allAttendees, t);
 
+  const toFreeBusyAttendee = (a: userAttendee) => ({
+    email: a.cal_address,
+    userId: null,
+  });
+
+  const freeBusyMap = useAttendeesFreeBusy({
+    existingAttendees: allAttendees.map(toFreeBusyAttendee),
+    newAttendees: [],
+    start: start ?? "",
+    end: end ?? "",
+    timezone: timezone ?? "UTC",
+    eventUid,
+    enabled: !!(start && end && showAllAttendees),
+  });
+
+  const busyCaption = (a: userAttendee) =>
+    freeBusyMap[a.cal_address] === "busy"
+      ? t("event.freeBusy.busy")
+      : undefined;
+
   return (
     <>
       <Box display="flex" alignItems="flex-start">
@@ -78,10 +107,24 @@ export function EventPreviewAttendees({
 
       {showAllAttendees &&
         organizer &&
-        renderAttendeeBadge(organizer, "org", t, showAllAttendees, true)}
+        renderAttendeeBadge(
+          organizer,
+          "org",
+          t,
+          showAllAttendees,
+          true,
+          busyCaption(organizer)
+        )}
       {showAllAttendees &&
         attendees.map((a, idx) =>
-          renderAttendeeBadge(a, idx.toString(), t, showAllAttendees)
+          renderAttendeeBadge(
+            a,
+            idx.toString(),
+            t,
+            showAllAttendees,
+            false,
+            busyCaption(a)
+          )
         )}
     </>
   );
diff --git a/src/features/Events/EventPreview/EventPreviewDetails.tsx b/src/features/Events/EventPreview/EventPreviewDetails.tsx
index 04af345..41005e0 100644
--- a/src/features/Events/EventPreview/EventPreviewDetails.tsx
+++ b/src/features/Events/EventPreview/EventPreviewDetails.tsx
@@ -1,17 +1,13 @@
 import { InfoRow } from "@/components/Event/InfoRow";
-import { renderAttendeeBadge } from "@/components/Event/utils/eventUtils";
-import { AvatarGroup, Box, Button, Typography } from "@linagora/twake-mui";
+import { Box, Button, Typography } from "@linagora/twake-mui";
 import ErrorOutlineIcon from "@mui/icons-material/ErrorOutline";
 import LocationOnOutlinedIcon from "@mui/icons-material/LocationOnOutlined";
 import NotificationsNoneIcon from "@mui/icons-material/NotificationsNone";
-import PeopleAltOutlinedIcon from "@mui/icons-material/PeopleAltOutlined";
 import RepeatIcon from "@mui/icons-material/Repeat";
 import SubjectIcon from "@mui/icons-material/Subject";
 import VideocamOutlinedIcon from "@mui/icons-material/VideocamOutlined";
 import { alpha, useTheme } from "@mui/material/styles";
-import { useState } from "react";
 import { useI18n } from "twake-i18n";
-import { makeAttendeePreview } from ".";
 import { CalendarEvent } from "../EventsTypes";
 import { EventPreviewAttendees } from "./EventPreviewAttendees";
 import { makeRecurrenceString } from "./utils/makeRecurrenceString";
@@ -20,35 +16,26 @@ interface EventPreviewDetailsProps {
   event: CalendarEvent;
   isOwn: boolean;
   isNotPrivate: boolean;
-  userEmail: string;
 }
 
-const ATTENDEE_DISPLAY_LIMIT = 3;
-
 export function EventPreviewDetails({
   event,
   isOwn,
   isNotPrivate,
-  userEmail,
 }: EventPreviewDetailsProps) {
   const { t } = useI18n();
   const theme = useTheme();
   const infoIconColor = alpha(theme.palette.grey[900], 0.9);
   const infoIconSx = { minWidth: "25px", marginRight: 2, color: infoIconColor };
 
-  const [showAllAttendees, setShowAllAttendees] = useState(false);
-
   const attendees =
     event.attendee?.filter(
       (a) => a.cal_address !== event.organizer?.cal_address
     ) || [];
-
   const organizer = event.attendee?.find(
     (a) => a.cal_address === event.organizer?.cal_address
   );
-
-  const attendeePreview = makeAttendeePreview(event.attendee, t);
-  const showDetails = (isNotPrivate && !isOwn) || isOwn;
+  const showDetails = isNotPrivate || isOwn;
 
   if (!showDetails) {
     return (
@@ -84,7 +71,13 @@ export function EventPreviewDetails({
             <Button
               variant="contained"
               size="medium"
-              onClick={() => window.open(event.x_openpass_videoconference)}
+              onClick={() =>
+                window.open(
+                  event.x_openpass_videoconference,
+                  "_blank",
+                  "noopener,noreferrer"
+                )
+              }
               sx={{ borderRadius: "4px" }}
             >
               {t("eventPreview.joinVideo")}
@@ -98,7 +91,11 @@ export function EventPreviewDetails({
         <EventPreviewAttendees
           attendees={attendees}
           organizer={organizer}
-          allAttendees={event.attendee}
+          allAttendees={event.attendee ?? []}
+          start={event.start}
+          end={event.end}
+          timezone={event.timezone}
+          eventUid={event.uid}
         />
       )}
 
diff --git a/src/features/Events/EventPreview/EventPreviewHeader.tsx b/src/features/Events/EventPreview/EventPreviewHeader.tsx
index 8bd3cc3..79e0b8c 100644
--- a/src/features/Events/EventPreview/EventPreviewHeader.tsx
+++ b/src/features/Events/EventPreview/EventPreviewHeader.tsx
@@ -1,10 +1,10 @@
-import { dlEvent } from "../EventApi";
-import { CalendarEvent } from "../EventsTypes";
 import { Box, IconButton } from "@linagora/twake-mui";
 import CloseIcon from "@mui/icons-material/Close";
 import EditIcon from "@mui/icons-material/Edit";
 import FileDownloadOutlinedIcon from "@mui/icons-material/FileDownloadOutlined";
 import MoreVertIcon from "@mui/icons-material/MoreVert";
+import { dlEvent } from "../EventApi";
+import { CalendarEvent } from "../EventsTypes";
 
 interface EventPreviewHeaderProps {
   event: CalendarEvent;
@@ -13,7 +13,6 @@ interface EventPreviewHeaderProps {
   isOwn: boolean;
   isWriteDelegated: boolean;
   isNotPrivate: boolean;
-  isRecurring: boolean;
   onClose: () => void;
   onEdit: () => void;
   onMoreClick: (e: React.MouseEvent<HTMLElement>) => void;
@@ -26,13 +25,12 @@ export function EventPreviewHeader({
   isOwn,
   isWriteDelegated,
   isNotPrivate,
-  isRecurring,
   onClose,
   onEdit,
   onMoreClick,
 }: EventPreviewHeaderProps) {
   const canEdit = isOrganizer && (isOwn || (isWriteDelegated && isNotPrivate));
-  const canSeeMore = (isNotPrivate && !isOwn) || isOwn;
+  const canSeeMore = isNotPrivate || isOwn;
 
   return (
     <Box
diff --git a/src/features/Events/EventPreview/EventPreviewModal.tsx b/src/features/Events/EventPreview/EventPreviewModal.tsx
index 6b686e9..1b26e11 100644
--- a/src/features/Events/EventPreview/EventPreviewModal.tsx
+++ b/src/features/Events/EventPreview/EventPreviewModal.tsx
@@ -1,9 +1,8 @@
-import { useAppSelector } from "@/app/hooks";
 import { CalendarName } from "@/components/Calendar/CalendarName";
 import { formatEventChipTitle } from "@/components/Calendar/utils/calendarUtils";
 import ResponsiveDialog from "@/components/Dialog/ResponsiveDialog";
 import { EditModeDialog } from "@/components/Event/EditModeDialog";
-import { browserDefaultTimeZone, getTimezoneOffset } from "@/utils/timezone";
+import { getTimezoneOffset } from "@/utils/timezone";
 import { DateSelectArg } from "@fullcalendar/core";
 import { Box, Chip, Tooltip, Typography } from "@linagora/twake-mui";
 import CircleIcon from "@mui/icons-material/Circle";
@@ -12,13 +11,13 @@ import { useEffect } from "react";
 import { useI18n } from "twake-i18n";
 import { AttendanceValidation } from "../AttendanceValidation/AttendanceValidation";
 import EventPopover from "../EventModal";
-import EventUpdateModal from "../EventUpdateModal";
 import { EventPreviewActionMenu } from "../EventPreview/EventPreviewActionMenu";
 import { EventPreviewDetails } from "../EventPreview/EventPreviewDetails";
 import { EventPreviewHeader } from "../EventPreview/EventPreviewHeader";
 import { useEventPreviewState } from "../EventPreview/useEventPreviewState";
-import { formatEnd } from "./utils/formatEnd";
+import EventUpdateModal from "../EventUpdateModal";
 import { formatDate } from "./utils/formatDate";
+import { formatEnd } from "./utils/formatEnd";
 
 export default function EventPreviewModal({
   eventId,
@@ -42,7 +41,6 @@ export default function EventPreviewModal({
     timezone,
     contextualizedEvent,
     attendanceUser,
-    isRecurring,
     isOwn,
     isWriteDelegated,
     isOrganizer,
@@ -57,7 +55,6 @@ export default function EventPreviewModal({
     setToggleActionMenu,
     openEditModePopup,
     setOpenEditModePopup,
-    typeOfAction,
     setTypeOfAction,
     afterChoiceFunc,
     setAfterChoiceFunc,
@@ -67,11 +64,14 @@ export default function EventPreviewModal({
     handleDuplicateClick,
   } = useEventPreviewState(eventId, calId, tempEvent, open, onClose);
 
-  useEffect(() => {
-    if (!event || !calendar) {
-      onClose({}, "backdropClick");
-    }
-  }, [event, calendar, onClose]);
+  useEffect(
+    () => {
+      if (open && (!event || !calendar)) {
+        onClose({}, "backdropClick");
+      }
+    }, // eslint-disable-next-line react-hooks/exhaustive-deps
+    [open, event, calendar]
+  );
 
   if (!user || !event || !calendar) return null;
 
@@ -94,7 +94,6 @@ export default function EventPreviewModal({
             isOwn={isOwn}
             isWriteDelegated={isWriteDelegated}
             isNotPrivate={isNotPrivate}
-            isRecurring={isRecurring}
             onClose={() => onClose({}, "backdropClick")}
             onEdit={handleEditClick}
             onMoreClick={(e) => setToggleActionMenu(e.currentTarget)}
@@ -164,7 +163,6 @@ export default function EventPreviewModal({
           event={event}
           isOwn={isOwn}
           isNotPrivate={isNotPrivate}
-          userEmail={user.email}
         />
 
         {/* Calendar label */}
@@ -219,8 +217,8 @@ export default function EventPreviewModal({
           {
             start: new Date(event.start),
             startStr: event.start,
-            end: new Date(event.end ?? ""),
-            endStr: event.end ?? "",
+            end: new Date(event.end ?? event.start),
+            endStr: event.end ?? event.start,
             allDay: event.allday ?? false,
           } as DateSelectArg
         }
diff --git a/src/features/Events/EventPreview/useEventPreviewState.ts b/src/features/Events/EventPreview/useEventPreviewState.ts
index 66041cb..23eed24 100644
--- a/src/features/Events/EventPreview/useEventPreviewState.ts
+++ b/src/features/Events/EventPreview/useEventPreviewState.ts
@@ -138,7 +138,7 @@ export function useEventPreviewState(
         const result = await dispatch(
           deleteEventAsync({ calId, eventId, eventURL: event.URL })
         );
-        assertThunkSuccess(result);
+        await assertThunkSuccess(result);
       } catch (error) {
         console.error("Failed to delete event:", error);
       }
diff --git a/src/features/Events/EventPreview/utils/makeAttendeePreview.ts b/src/features/Events/EventPreview/utils/makeAttendeePreview.ts
index 176fc73..c3ba6ed 100644
--- a/src/features/Events/EventPreview/utils/makeAttendeePreview.ts
+++ b/src/features/Events/EventPreview/utils/makeAttendeePreview.ts
@@ -1,18 +1,27 @@
-import { userAttendee } from "@/src/features/User/models/attendee";
+import { userAttendee } from "@/features/User/models/attendee";
 
 export function makeAttendeePreview(
-  attendees: userAttendee[],
+  attendees: userAttendee[] | undefined,
   t: (k: string, p?: string | object) => string
 ) {
   const attendeePreview = [];
-  const yesCount = attendees?.filter((a) => a.partstat === "ACCEPTED").length;
-  const noCount = attendees?.filter((a) => a.partstat === "DECLINED").length;
-  const maybeCount = attendees?.filter(
-    (a) => a.partstat === "TENTATIVE"
-  ).length;
-  const needActionCount = attendees?.filter(
-    (a) => a.partstat === "NEEDS-ACTION"
-  ).length;
+  const counts = (attendees ?? []).reduce(
+    (acc, a) => {
+      if (a.partstat === "ACCEPTED") acc.yes++;
+      else if (a.partstat === "DECLINED") acc.no++;
+      else if (a.partstat === "TENTATIVE") acc.maybe++;
+      else if (a.partstat === "NEEDS-ACTION") acc.needAction++;
+      return acc;
+    },
+    { yes: 0, no: 0, maybe: 0, needAction: 0 }
+  );
+  const {
+    yes: yesCount,
+    no: noCount,
+    maybe: maybeCount,
+    needAction: needActionCount,
+  } = counts;
+
   if (yesCount) {
     attendeePreview.push(t("eventPreview.yesCount", { count: yesCount }));
   }
diff --git a/src/features/Events/api/getFreeBusyForEventAttendeesPOST.ts b/src/features/Events/api/getFreeBusyForEventAttendeesPOST.ts
index 8a18564..322a424 100644
--- a/src/features/Events/api/getFreeBusyForEventAttendeesPOST.ts
+++ b/src/features/Events/api/getFreeBusyForEventAttendeesPOST.ts
@@ -1,4 +1,21 @@
 import { api } from "@/utils/apiUtils";
+import { extractEventBaseUuid } from "@/utils/extractEventBaseUuid";
+
+interface BusySlot {
+  uid: string;
+  start: string;
+  end: string;
+}
+
+interface CalendarFreeBusy {
+  id: string;
+  busy: BusySlot[];
+}
+
+interface UserFreeBusy {
+  id: string;
+  calendars: CalendarFreeBusy[];
+}
 
 export async function getFreeBusyForEventAttendeesPOST(
   userIds: string[],
@@ -13,10 +30,16 @@ export async function getFreeBusyForEventAttendeesPOST(
   });
   if (!r.ok) throw new Error(`HTTP ${r.status}`);
 
-  const { users } = (await r.json()) as {
-    users: { id: string; calendars: { busy: unknown[] }[] }[];
-  };
+  const { users } = (await r.json()) as { users: UserFreeBusy[] };
+
+  const eventUidBase = extractEventBaseUuid(eventUid);
+
   return Object.fromEntries(
-    users.map((u) => [u.id, u.calendars.some((cal) => cal.busy.length > 0)])
+    users.map((u) => {
+      const isBusy = u.calendars.some((cal) =>
+        cal.busy.some((slot) => extractEventBaseUuid(slot.uid) !== eventUidBase)
+      );
+      return [u.id, isBusy];
+    })
   );
 }