diff --git a/lib/handlers/on-copy.js b/lib/handlers/on-copy.js
index d4d21f2..896b345 100644
--- a/lib/handlers/on-copy.js
+++ b/lib/handlers/on-copy.js
@@ -77,11 +77,12 @@ module.exports = (server, messageHandler) => (mailbox, update, session, callback
 
                                 if (r && r.value) {
                                     server.loggelf({
-                                        short_message: '[QUOTA CHANGE]',
+                                        short_message: '[QUOTA CHANGE] Quota usage increased',
+                                        _mail_action: 'quota',
                                         _user: mailboxData.user,
                                         _inc: -copiedStorage,
                                         _copied_messages: copiedMessages,
-                                        _storageUsed: r.value.storageUsed,
+                                        _storage_used: r.value.storageUsed,
                                         _session: session && session.id
                                     });
                                 }
diff --git a/lib/message-handler.js b/lib/message-handler.js
index 8c53edf..5a0064e 100644
--- a/lib/message-handler.js
+++ b/lib/message-handler.js
@@ -234,6 +234,7 @@ class MessageHandler {
                             // join lines
                             .replace(/\s+/g, ' ')
                             .trim();
+
                         if (messageData.intro.length > 128) {
                             let intro = messageData.intro.substr(0, 128);
                             let lastSp = intro.lastIndexOf(' ');
@@ -286,10 +287,11 @@ class MessageHandler {
 
                             if (r && r.value) {
                                 this.loggelf({
-                                    short_message: '[QUOTA CHANGE]',
+                                    short_message: '[QUOTA CHANGE] Quota usage increased',
+                                    _mail_action: 'quota',
                                     _user: mailboxData.user,
                                     _inc: size,
-                                    _storageUsed: r.value.storageUsed,
+                                    _storage_used: r.value.storageUsed,
                                     _session: options.session && options.session.id
                                 });
                             }
@@ -315,10 +317,11 @@ class MessageHandler {
 
                                         if (r && r.value) {
                                             this.loggelf({
-                                                short_message: '[QUOTA CHANGE]',
+                                                short_message: '[QUOTA CHANGE] Quota usage decreased',
+                                                _mail_action: 'quota',
                                                 _user: mailboxData.user,
                                                 _inc: -size,
-                                                _storageUsed: r.value.storageUsed,
+                                                _storage_used: r.value.storageUsed,
                                                 _session: options.session && options.session.id,
                                                 _rollback: 'yes',
                                                 _error: err.message,
@@ -466,10 +469,11 @@ class MessageHandler {
 
                 if (r && r.value) {
                     this.loggelf({
-                        short_message: '[QUOTA CHANGE]',
+                        short_message: '[QUOTA CHANGE] Quota usage ' + (Number(inc.storageUsed) || 0 < 0 ? 'decreased' : 'increased'),
+                        _mail_action: 'quota',
                         _user: user,
                         _inc: inc.storageUsed,
-                        _storageUsed: r.value.storageUsed,
+                        _storage_used: r.value.storageUsed,
                         _session: options.session && options.session.id
                     });
                 }
diff --git a/lib/tasks/quota.js b/lib/tasks/quota.js
index df0dc94..38ed3a2 100644
--- a/lib/tasks/quota.js
+++ b/lib/tasks/quota.js
@@ -59,7 +59,7 @@ module.exports = (taskData, options, callback) => {
                         return setImmediate(processNext);
                     }
 
-                    db.users.collection('users').updateOne(
+                    db.users.collection('users').findOneAndUpdate(
                         {
                             _id: userData._id
                         },
@@ -68,11 +68,30 @@ module.exports = (taskData, options, callback) => {
                                 storageUsed: Number(storageUsed) || 0
                             }
                         },
+                        {
+                            returnOriginal: true,
+                            projection: {
+                                storageUsed: true
+                            }
+                        },
                         (err, r) => {
                             if (err) {
                                 log.error('Tasks', 'task=quota id=%s user=%s error=%s', taskData._id, userData._id, err.message);
                                 return setTimeout(processNext, 5000);
                             }
+
+                            if (r && r.value) {
+                                options.loggelf({
+                                    short_message: '[QUOTA CHANGE] Quota usage recalculated',
+                                    _mail_action: 'quota',
+                                    _user: userData._id,
+                                    _set: Number(storageUsed) || 0,
+                                    _previous_storage_used: r.value.storageUsed,
+                                    _storage_used: Number(storageUsed) || 0,
+                                    _session: 'task.quota.' + taskData._id
+                                });
+                            }
+
                             log.info(
                                 'Tasks',
                                 'task=quota id=%s user=%s stored=%s calculated=%s updated=%s',
@@ -80,7 +99,7 @@ module.exports = (taskData, options, callback) => {
                                 userData._id,
                                 userData.storageUsed,
                                 storageUsed,
-                                r.modifiedCount ? 'yes' : 'no'
+                                r.lastErrorObject && r.lastErrorObject.updatedExisting ? 'yes' : 'no'
                             );
                             return setImmediate(processNext);
                         }
diff --git a/tasks.js b/tasks.js
index 6a0a275..f0603a8 100644
--- a/tasks.js
+++ b/tasks.js
@@ -9,6 +9,8 @@ const yaml = require('js-yaml');
 const fs = require('fs');
 const MessageHandler = require('./lib/message-handler');
 const setupIndexes = yaml.safeLoad(fs.readFileSync(__dirname + '/indexes.yaml', 'utf8'));
+const Gelf = require('gelf');
+const os = require('os');
 
 const taskRestore = require('./lib/tasks/restore');
 const taskUserDelete = require('./lib/tasks/user-delete');
@@ -18,12 +20,52 @@ let messageHandler;
 let gcTimeout;
 let taskTimeout;
 let gcLock;
+let loggelf;
 
 module.exports.start = callback => {
     if (!config.tasks.enabled) {
         return setImmediate(() => callback(null, false));
     }
 
+    const component = config.log.gelf.component || 'wildduck';
+    const hostname = config.log.gelf.hostname || os.hostname();
+    const gelf =
+        config.log.gelf && config.log.gelf.enabled
+            ? new Gelf(config.log.gelf.options)
+            : {
+                  // placeholder
+                  emit: () => false
+              };
+
+    loggelf = message => {
+        if (typeof message === 'string') {
+            message = {
+                short_message: message
+            };
+        }
+
+        message = message || {};
+
+        if (!message.short_message || message.short_message.indexOf(component.toUpperCase()) !== 0) {
+            message.short_message = component.toUpperCase() + ' ' + (message.short_message || '');
+        }
+
+        message.facility = component; // facility is deprecated but set by the driver if not provided
+        message.host = hostname;
+        message.timestamp = Date.now() / 1000;
+        message._component = component;
+        Object.keys(message).forEach(key => {
+            if (!message[key]) {
+                delete message[key];
+            }
+        });
+        try {
+            gelf.emit('gelf.log', message);
+        } catch (err) {
+            log.error('Gelf', err);
+        }
+    };
+
     gcLock = new RedFour({
         redis: db.redis,
         namespace: 'wildduck'
@@ -454,7 +496,8 @@ function processTask(taskData, callback) {
             return taskRestore(
                 taskData,
                 {
-                    messageHandler
+                    messageHandler,
+                    loggelf
                 },
                 err => {
                     if (err) {
@@ -465,7 +508,7 @@ function processTask(taskData, callback) {
                 }
             );
         case 'user-delete':
-            return taskUserDelete(taskData, {}, err => {
+            return taskUserDelete(taskData, { loggelf }, err => {
                 if (err) {
                     return callback(err);
                 }
@@ -473,7 +516,7 @@ function processTask(taskData, callback) {
                 callback(null, true);
             });
         case 'quota':
-            return taskQuota(taskData, {}, err => {
+            return taskQuota(taskData, { loggelf }, err => {
                 if (err) {
                     return callback(err);
                 }