diff --git a/src/components/views/rooms/NotificationBadge.tsx b/src/components/views/rooms/NotificationBadge.tsx
index 8329de7391..a70ff93bd2 100644
--- a/src/components/views/rooms/NotificationBadge.tsx
+++ b/src/components/views/rooms/NotificationBadge.tsx
@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import React from "react";
+import React, { MouseEvent } from "react";
 import classNames from "classnames";
 import { formatCount } from "../../../utils/FormattingUtils";
 import SettingsStore from "../../../settings/SettingsStore";
@@ -22,6 +22,9 @@ import AccessibleButton from "../elements/AccessibleButton";
 import { XOR } from "../../../@types/common";
 import { NOTIFICATION_STATE_UPDATE, NotificationState } from "../../../stores/notifications/NotificationState";
 import { replaceableComponent } from "../../../utils/replaceableComponent";
+import Tooltip from "../elements/Tooltip";
+import { _t } from "../../../languageHandler";
+import { NotificationColor } from "../../../stores/notifications/NotificationColor";
 
 interface IProps {
     notification: NotificationState;
@@ -39,6 +42,7 @@ interface IProps {
 }
 
 interface IClickableProps extends IProps, React.InputHTMLAttributes<Element> {
+    showUnsentTooltip?: boolean;
     /**
      * If specified will return an AccessibleButton instead of a div.
      */
@@ -47,6 +51,7 @@ interface IClickableProps extends IProps, React.InputHTMLAttributes<Element> {
 
 interface IState {
     showCounts: boolean; // whether or not to show counts. Independent of props.forceCount
+    showTooltip: boolean;
 }
 
 @replaceableComponent("views.rooms.NotificationBadge")
@@ -59,6 +64,7 @@ export default class NotificationBadge extends React.PureComponent<XOR<IProps, I
 
         this.state = {
             showCounts: SettingsStore.getValue("Notifications.alwaysShowBadgeCounts", this.roomId),
+            showTooltip: false,
         };
 
         this.countWatcherRef = SettingsStore.watchSetting(
@@ -93,9 +99,22 @@ export default class NotificationBadge extends React.PureComponent<XOR<IProps, I
         this.forceUpdate(); // notification state changed - update
     };
 
+    private onMouseOver = (e: MouseEvent) => {
+        e.stopPropagation();
+        this.setState({
+            showTooltip: true,
+        });
+    };
+
+    private onMouseLeave = () => {
+        this.setState({
+            showTooltip: false,
+        });
+    };
+
     public render(): React.ReactElement {
         /* eslint @typescript-eslint/no-unused-vars: ["error", { "ignoreRestSiblings": true }] */
-        const { notification, forceCount, roomId, onClick, ...props } = this.props;
+        const { notification, showUnsentTooltip, forceCount, roomId, onClick, ...props } = this.props;
 
         // Don't show a badge if we don't need to
         if (notification.isIdle) return null;
@@ -124,9 +143,23 @@ export default class NotificationBadge extends React.PureComponent<XOR<IProps, I
         });
 
         if (onClick) {
+            let tooltip;
+            if (showUnsentTooltip && this.state.showTooltip && notification.color === NotificationColor.Unsent) {
+                tooltip = (
+                    <Tooltip className="mx_RoleButton_tooltip" label={_t("Message didn't send. Click for info.")} />
+                );
+            }
+
             return (
-                <AccessibleButton {...props} className={classes} onClick={onClick}>
+                <AccessibleButton
+                    {...props}
+                    className={classes}
+                    onClick={onClick}
+                    onMouseOver={this.onMouseOver}
+                    onMouseLeave={this.onMouseLeave}
+                >
                     <span className="mx_NotificationBadge_count">{ symbol }</span>
+                    { tooltip }
                 </AccessibleButton>
             );
         }
diff --git a/src/components/views/spaces/SpaceTreeLevel.tsx b/src/components/views/spaces/SpaceTreeLevel.tsx
index dda58ae944..f9d901a298 100644
--- a/src/components/views/spaces/SpaceTreeLevel.tsx
+++ b/src/components/views/spaces/SpaceTreeLevel.tsx
@@ -93,6 +93,7 @@ export const SpaceButton: React.FC<IButtonProps> = ({
                 notification={notificationState}
                 aria-label={ariaLabel}
                 tabIndex={tabIndex}
+                showUnsentTooltip={true}
             />
         </div>;
     }
diff --git a/src/i18n/strings/en_EN.json b/src/i18n/strings/en_EN.json
index deb854868f..ff5eb29f99 100644
--- a/src/i18n/strings/en_EN.json
+++ b/src/i18n/strings/en_EN.json
@@ -1587,6 +1587,7 @@
     "Your private messages are normally encrypted, but this room isn't. Usually this is due to an unsupported device or method being used, like email invites.": "Your private messages are normally encrypted, but this room isn't. Usually this is due to an unsupported device or method being used, like email invites.",
     "Enable encryption in settings.": "Enable encryption in settings.",
     "End-to-end encryption isn't enabled": "End-to-end encryption isn't enabled",
+    "Message didn't send. Click for info.": "Message didn't send. Click for info.",
     "Unpin": "Unpin",
     "View message": "View message",
     "%(duration)ss": "%(duration)ss",
diff --git a/src/stores/notifications/NotificationColor.ts b/src/stores/notifications/NotificationColor.ts
index b12f2b7c00..fadd5ac67e 100644
--- a/src/stores/notifications/NotificationColor.ts
+++ b/src/stores/notifications/NotificationColor.ts
@@ -21,4 +21,5 @@ export enum NotificationColor {
     Bold, // no badge, show as unread
     Grey, // unread notified messages
     Red,  // unread pings
+    Unsent, // some messages failed to send
 }
diff --git a/src/stores/notifications/RoomNotificationState.ts b/src/stores/notifications/RoomNotificationState.ts
index 0a2e801620..d0479200bd 100644
--- a/src/stores/notifications/RoomNotificationState.ts
+++ b/src/stores/notifications/RoomNotificationState.ts
@@ -88,7 +88,7 @@ export class RoomNotificationState extends NotificationState implements IDestroy
 
         if (getUnsentMessages(this.room).length > 0) {
             // When there are unsent messages we show a red `!`
-            this._color = NotificationColor.Red;
+            this._color = NotificationColor.Unsent;
             this._symbol = "!";
             this._count = 1; // not used, technically
         } else if (RoomNotifs.getRoomNotifsState(this.room.roomId) === RoomNotifs.MUTE) {
diff --git a/src/stores/notifications/SpaceNotificationState.ts b/src/stores/notifications/SpaceNotificationState.ts
index f8eb07251b..c414a01fc2 100644
--- a/src/stores/notifications/SpaceNotificationState.ts
+++ b/src/stores/notifications/SpaceNotificationState.ts
@@ -30,10 +30,6 @@ export class SpaceNotificationState extends NotificationState {
         super();
     }
 
-    public get symbol(): string {
-        return null; // This notification state doesn't support symbols
-    }
-
     public setRooms(rooms: Room[]) {
         const oldRooms = this.rooms;
         const diff = arrayDiff(oldRooms, rooms);
@@ -54,7 +50,7 @@ export class SpaceNotificationState extends NotificationState {
     }
 
     public getFirstRoomWithNotifications() {
-        return this.rooms.find((room) => room.getUnreadNotificationCount() > 0).roomId;
+        return Object.values(this.states).find(state => state.color >= this.color)?.room.roomId;
     }
 
     public destroy() {
@@ -79,6 +75,8 @@ export class SpaceNotificationState extends NotificationState {
             this._color = Math.max(this.color, state.color);
         }
 
+        this._symbol = this._color === NotificationColor.Unsent ? "!" : null;
+
         // finally, publish an update if needed
         this.emitIfUpdated(snapshot);
     }