diff --git a/CHANGES b/CHANGES
index 40c7eca89..eede7bb7e 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1530,4 +1530,5 @@
 * Mailbox and lists UI is now always visible (but disabled) when incoming email is disabled
 * Fix issue where long passwords were not accepted
 * DNS and backup credential secrets are not returned in API calls anymore
+* Send notification when an app that went down, came back up
 
diff --git a/src/apphealthmonitor.js b/src/apphealthmonitor.js
index 7ab762968..7eab185b9 100644
--- a/src/apphealthmonitor.js
+++ b/src/apphealthmonitor.js
@@ -17,7 +17,7 @@ exports = module.exports = {
 
 const HEALTHCHECK_INTERVAL = 10 * 1000; // every 10 seconds. this needs to be small since the UI makes only healthy apps clickable
 const UNHEALTHY_THRESHOLD = 10 * 60 * 1000; // 10 minutes
-let gHealthInfo = { }; // { time, emailSent }
+let gHealthInfo = { }; // { time, appDownEvent }
 
 const OOM_MAIL_LIMIT = 60 * 60 * 1000; // 60 minutes
 let gLastOomMailTime = Date.now() - (5 * 60 * 1000); // pretend we sent email 5 minutes ago
@@ -36,22 +36,28 @@ function setHealth(app, health, callback) {
     var now = new Date();
 
     if (!(app.id in gHealthInfo)) { // add new apps to list
-        gHealthInfo[app.id] = { time: now, emailSent: false };
+        gHealthInfo[app.id] = { time: now, appDownEvent: false };
     }
 
     if (health === appdb.HEALTH_HEALTHY) {
         gHealthInfo[app.id].time = now;
+        if (!gHealthInfo[app.id].appDownEvent) return callback(null);
+
+        // do not send mails for dev apps
+        if (!app.debugMode) eventlog.add(eventlog.ACTION_APP_UP, { app: app }, {});
+
+        gHealthInfo[app.id].appDownEvent = false;
     } else if (Math.abs(now - gHealthInfo[app.id].time) > UNHEALTHY_THRESHOLD) {
-        if (gHealthInfo[app.id].emailSent) return callback(null);
+        if (gHealthInfo[app.id].appDownEvent) return callback(null);
 
         debugApp(app, 'marking as unhealthy since not seen for more than %s minutes', UNHEALTHY_THRESHOLD/(60 * 1000));
 
         // do not send mails for dev apps
         if (!app.debugMode) eventlog.add(eventlog.ACTION_APP_DOWN, { app: app }, {});
 
-        gHealthInfo[app.id].emailSent = true;
+        gHealthInfo[app.id].appDownEvent = true;
     } else {
-        debugApp(app, 'waiting for sometime to update the app health');
+        debugApp(app, 'waiting for %s seconds to update the app health', (Math.abs(now - gHealthInfo[app.id].time) - UNHEALTHY_THRESHOLD)/1000);
         return callback(null);
     }
 
diff --git a/src/eventlog.js b/src/eventlog.js
index 19d4193b7..0a6891aaa 100644
--- a/src/eventlog.js
+++ b/src/eventlog.js
@@ -19,6 +19,7 @@ exports = module.exports = {
     ACTION_APP_UPDATE: 'app.update',
     ACTION_APP_LOGIN: 'app.login',
     ACTION_APP_OOM: 'app.oom',
+    ACTION_APP_UP: 'app.up',
     ACTION_APP_DOWN: 'app.down',
     ACTION_APP_TASK_CRASH: 'app.task.crash',
 
@@ -115,6 +116,8 @@ function add(action, source, data, callback) {
             notifications.oomEvent(id, source.app ? source.app.id : source.containerId, { app: source.app, details: data });
         } else if (action === exports.ACTION_APP_DOWN) {
             notifications.appDied(id, source.app);
+        } else if (action === exports.ACTION_APP_UP) {
+            notifications.appUp(id, source.app);
         } else if (action === exports.ACTION_APP_TASK_CRASH) {
             notifications.apptaskCrash(id, source.appId, data.crashLogFile);
         } else if (action === exports.ACTION_PROCESS_CRASH) {
diff --git a/src/mail_templates/app_up.ejs b/src/mail_templates/app_up.ejs
new file mode 100644
index 000000000..9d842ab58
--- /dev/null
+++ b/src/mail_templates/app_up.ejs
@@ -0,0 +1,14 @@
+<%if (format === 'text') { %>
+
+Dear Cloudron Admin,
+
+The application '<%= title %>' installed at <%= appFqdn %> is back online
+and responding to health checks.
+
+Powered by https://cloudron.io
+
+Sent at: <%= new Date().toUTCString() %>
+
+<% } else { %>
+
+<% } %>
diff --git a/src/mailer.js b/src/mailer.js
index 7db8136dc..566a068a8 100644
--- a/src/mailer.js
+++ b/src/mailer.js
@@ -12,6 +12,7 @@ exports = module.exports = {
     sendInvite: sendInvite,
     unexpectedExit: unexpectedExit,
 
+    appUp: appUp,
     appDied: appDied,
     oomEvent: oomEvent,
 
@@ -311,6 +312,26 @@ function passwordReset(user) {
     });
 }
 
+function appUp(mailTo, app) {
+    assert.strictEqual(typeof mailTo, 'string');
+    assert.strictEqual(typeof app, 'object');
+
+    debug('Sending mail for app %s @ %s up', app.id, app.fqdn);
+
+    getMailConfig(function (error, mailConfig) {
+        if (error) return debug('Error getting mail details:', error);
+
+        var mailOptions = {
+            from: mailConfig.notificationFrom,
+            to: mailTo,
+            subject: util.format('[%s] App %s is back online', mailConfig.cloudronName, app.fqdn),
+            text: render('app_up.ejs', { title: app.manifest.title, appFqdn: app.fqdn, format: 'text' })
+        };
+
+        enqueue(mailOptions);
+    });
+}
+
 function appDied(mailTo, app) {
     assert.strictEqual(typeof mailTo, 'string');
     assert.strictEqual(typeof app, 'object');
diff --git a/src/notifications.js b/src/notifications.js
index ac961907f..9519d24f8 100644
--- a/src/notifications.js
+++ b/src/notifications.js
@@ -14,6 +14,7 @@ exports = module.exports = {
     userRemoved: userRemoved,
     adminChanged: adminChanged,
     oomEvent: oomEvent,
+    appUp: appUp,
     appDied: appDied,
     processCrash: processCrash,
     apptaskCrash: apptaskCrash,
@@ -219,6 +220,21 @@ function oomEvent(eventId, program, context) {
     });
 }
 
+function appUp(eventId, app) {
+    assert.strictEqual(typeof eventId, 'string');
+    assert.strictEqual(typeof app, 'object');
+
+    // also send us a notification mail
+    if (config.provider() === 'caas') mailer.appDied('support@cloudron.io', app);
+
+    actionForAllAdmins([], function (admin, callback) {
+        mailer.appUp(admin.email, app);
+        add(admin.id, eventId, `App ${app.fqdn} is back online`, `The application ${app.manifest.title} installed at ${app.fqdn} is back online.`, '/#/apps', callback);
+    }, function (error) {
+        if (error) console.error(error);
+    });
+}
+
 function appDied(eventId, app) {
     assert.strictEqual(typeof eventId, 'string');
     assert.strictEqual(typeof app, 'object');