diff --git a/addons/im_livechat/views/im_livechat_channel_templates.xml b/addons/im_livechat/views/im_livechat_channel_templates.xml
index ff9b5ab1e25..e40a311c892 100644
--- a/addons/im_livechat/views/im_livechat_channel_templates.xml
+++ b/addons/im_livechat/views/im_livechat_channel_templates.xml
@@ -135,6 +135,7 @@
             <script type="text/javascript" src="/bus/static/src/js/bus.js"></script>
             <script type="text/javascript" src="/mail/static/src/js/chat_window.js"></script>
             <script type="text/javascript" src="/mail/static/src/js/thread.js"></script>
+            <script type="text/javascript" src="/mail/static/src/js/document_viewer.js"></script>
             <script type="text/javascript" src="/im_livechat/static/src/js/im_livechat.js"></script>
             <t t-call="web.less_helpers"/>
             <link rel="stylesheet" href="/im_livechat/static/src/less/im_livechat_bootstrap.less"/>
diff --git a/addons/mail/controllers/main.py b/addons/mail/controllers/main.py
index c1b4433e74a..6146b5b37e5 100644
--- a/addons/mail/controllers/main.py
+++ b/addons/mail/controllers/main.py
@@ -2,7 +2,6 @@
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
 import base64
-import json
 import logging
 import psycopg2
 import werkzeug
diff --git a/addons/mail/static/src/js/composer.js b/addons/mail/static/src/js/composer.js
index 29806a08e51..f4ba98696a5 100644
--- a/addons/mail/static/src/js/composer.js
+++ b/addons/mail/static/src/js/composer.js
@@ -2,6 +2,7 @@ odoo.define('mail.composer', function (require) {
 "use strict";
 
 var chat_mixin = require('mail.chat_mixin');
+var DocumentViewer = require('mail.DocumentViewer');
 var utils = require('mail.utils');
 
 var core = require('web.core');
@@ -354,6 +355,8 @@ var BasicComposer = Widget.extend(chat_mixin, {
         "click .o_composer_button_send": "send_message",
         "click .o_composer_button_add_attachment": "on_click_add_attachment",
         "click .o_attachment_delete": "on_attachment_delete",
+        "click .o_attachment_download": "_onAttachmentDownload",
+        "click .o_attachment_view": "_onAttachmentView",
     },
     // RPCs done to fetch the mention suggestions are throttled with the following value
     MENTION_THROTTLE: 200,
@@ -758,6 +761,29 @@ var BasicComposer = Widget.extend(chat_mixin, {
     focus: function () {
         this.$input.focus();
     },
+    //--------------------------------------------------------------------------
+    // Handlers
+    //--------------------------------------------------------------------------
+
+    /**
+     * @private
+     * @param {MouseEvent} event
+     */
+    _onAttachmentDownload: function (event) {
+        event.stopPropagation();
+    },
+    /**
+     * @private
+     * @param {MouseEvent} event
+     */
+    _onAttachmentView: function (event) {
+        var activeAttachmentID = $(event.currentTarget).data('id');
+        var attachments = this.get('attachment_ids');
+        if (activeAttachmentID) {
+            var attachmentViewer = new DocumentViewer(this, attachments, activeAttachmentID);
+            attachmentViewer.appendTo($('body'));
+        }
+    },
 });
 
 var ExtendedComposer = BasicComposer.extend({
diff --git a/addons/mail/static/src/js/document_viewer.js b/addons/mail/static/src/js/document_viewer.js
new file mode 100644
index 00000000000..679e483c899
--- /dev/null
+++ b/addons/mail/static/src/js/document_viewer.js
@@ -0,0 +1,302 @@
+odoo.define('mail.DocumentViewer', function (require) {
+"use strict";
+
+var core = require('web.core');
+var Widget = require('web.Widget');
+
+var QWeb = core.qweb;
+
+var SCROLL_ZOOM_STEP = 0.1;
+var ZOOM_STEP = 0.5;
+
+var DocumentViewer = Widget.extend({
+    template: "DocumentViewer",
+    events: {
+        'click .o_download_btn': '_onDownload',
+        'click .o_viewer_img': '_onImageClicked',
+        'click .o_viewer_video': '_onVideoClicked',
+        'click .move_next': '_onNext',
+        'click .move_previous': '_onPrevious',
+        'click .o_zoom_in': '_onZoomIn',
+        'click .o_zoom_out': '_onZoomOut',
+        'click .o_close_btn, .o_viewer_img_wrapper': '_onClose',
+        'click .o_print_btn': '_onPrint',
+        'DOMMouseScroll .o_viewer_content': '_onScroll',    // Firefox
+        'mousewheel .o_viewer_content': '_onScroll',        // Chrome, Safari, IE
+        'keydown': '_onKeydown',
+        'mousedown .o_viewer_img': '_onStartDrag',
+        'mousemove .o_viewer_content': '_onDrag',
+        'mouseup .o_viewer_content': '_onEndDrag'
+    },
+    /**
+     * The documentViewer takes an array of objects describing attachments in
+     * argument, and the ID of an active attachment (the one to display first).
+     * Documents that are not of type image or video are filtered out.
+     *
+     * @override
+     * @param {Array[Object]} attachments list of attachments
+     * @param {integer} activeAttachmentID
+     */
+    init: function (parent, attachments, activeAttachmentID) {
+        this._super.apply(this, arguments);
+        this.attachment = _.filter(attachments, function (attachment) {
+            var type = attachment.mimetype.split('/').shift();
+            if (type === 'image' || type === 'video') {
+                attachment.type = type;
+                return true;
+            }
+        });
+        this.activeAttachment = _.findWhere(attachments, {id: activeAttachmentID});
+        this._reset();
+    },
+    /**
+     * Open a modal displaying the active attachment
+     * @override
+     */
+    start: function () {
+        this.$el.modal('show');
+        this.$el.on('hidden.bs.modal', _.bind(this._onDestroy, this));
+        this.$('.o_viewer_img').load(_.bind(this._onImageLoaded, this));
+        return this._super.apply(this, arguments);
+    },
+
+    //--------------------------------------------------------------------------
+    // Private
+    //---------------------------------------------------------------------------
+
+    /**
+     * @private
+     */
+    _next: function () {
+        var index = _.findIndex(this.attachment, this.activeAttachment);
+        index = (index + 1) % this.attachment.length;
+        this.activeAttachment = this.attachment[index];
+        this._updateContent();
+    },
+    /**
+     * @private
+     */
+    _previous: function () {
+        var index = _.findIndex(this.attachment, this.activeAttachment);
+        index = index === 0 ? this.attachment.length - 1 : index - 1;
+        this.activeAttachment = this.attachment[index];
+        this._updateContent();
+    },
+    /**
+     * @private
+     */
+    _reset: function () {
+        this.scale = 1;
+        this.dragStartX = this.dragstopX = 0;
+        this.dragStartY = this.dragstopY = 0;
+    },
+    /**
+     * Render the active attachment
+     *
+     * @private
+     */
+    _updateContent: function () {
+        this.$('.o_viewer_content').html(QWeb.render('DocumentViewer.Content', {
+            widget: this
+        }));
+        this.$('.o_viewer_img').load(_.bind(this._onImageLoaded, this));
+        this._reset();
+    },
+    /**
+     * Zoom in/out image by provided scale
+     *
+     * @private
+     * @param {integer} scale
+     */
+    _zoom: function (scale) {
+        if (scale > 0.5) {
+            this.$('.o_viewer_img').css('transform', 'scale3d(' + scale + ', ' + scale + ', 1)');
+            this.scale = scale;
+        }
+    },
+
+    //--------------------------------------------------------------------------
+    // Handlers
+    //--------------------------------------------------------------------------
+
+    /**
+     * @private
+     * @param {MouseEvent} e
+     */
+    _onClose: function (e) {
+        e.preventDefault();
+        this.$el.modal('hide');
+    },
+    /**
+     * When popup close complete destroyed modal even DOM footprint too
+     * @private
+     */
+    _onDestroy: function () {
+        if (this.isDestroyed()) {
+            return;
+        }
+        this.$el.modal('hide');
+        this.$el.remove();
+    },
+    /**
+     * @private
+     * @param {MouseEvent} e
+     */
+    _onDownload: function (e) {
+        e.preventDefault();
+        window.location = '/web/content/' + this.activeAttachment.id + '?download=true';
+    },
+    /**
+     * @private
+     * @param {MouseEvent} e
+     */
+    _onDrag: function (e) {
+        e.preventDefault();
+        if (this.enableDrag) {
+            var $image = this.$('.o_viewer_img');
+            var $zoomer = this.$('.o_viewer_zoomer');
+            var top = $image.prop('offsetHeight') * this.scale > $zoomer.height() ? e.clientY - this.dragStartY : 0;
+            var left = $image.prop('offsetWidth') * this.scale > $zoomer.width() ? e.clientX - this.dragStartX : 0;
+            $zoomer.css("transform", "translate3d("+ left +"px, " + top + "px, 0)");
+        }
+    },
+    /**
+     * @private
+     * @param {MouseEvent} e
+     */
+    _onEndDrag: function (e) {
+        e.preventDefault();
+        if (this.enableDrag) {
+            this.enableDrag = false;
+            this.dragstopX = e.clientX - this.dragStartX;
+            this.dragstopY = e.clientY - this.dragStartY;
+        }
+    },
+    /**
+     * On click of image do not close modal so stop event propagation
+     *
+     * @private
+     * @param {MouseEvent} e
+     */
+    _onImageClicked: function (e) {
+        e.stopPropagation();
+    },
+    /**
+     * Remove loading indicator when image loaded
+     * @private
+     */
+    _onImageLoaded: function () {
+        this.$('.o_loading_img').hide();
+    },
+    /**
+     * Move next previous attachment on keyboard right left key
+     *
+     * @private
+     * @param {KeyEvent} e
+     */
+    _onKeydown: function (e){
+        switch (e.which) {
+            case $.ui.keyCode.RIGHT:
+                e.preventDefault();
+                this._next();
+                break;
+            case $.ui.keyCode.LEFT:
+                e.preventDefault();
+                this._previous();
+                break;
+        }
+    },
+    /**
+     * @private
+     * @param {MouseEvent} e
+     */
+    _onNext: function (e) {
+        e.preventDefault();
+        this._next();
+    },
+    /**
+     * @private
+     * @param {MouseEvent} e
+     */
+    _onPrevious: function (e) {
+        e.preventDefault();
+        this._previous();
+    },
+    /**
+     * @private
+     * @param {MouseEvent} e
+     */
+    _onPrint: function (e) {
+        e.preventDefault();
+        var src = this.$('.o_viewer_img').prop('src');
+        var script = QWeb.render('PrintImage', {
+            src: src
+        });
+        var printWindow = window.open('about:blank', "_new");
+        printWindow.document.open();
+        printWindow.document.write(script);
+        printWindow.document.close();
+    },
+    /**
+     * Zoom image on scroll
+     *
+     * @private
+     * @param {MouseEvent} e
+     */
+    _onScroll: function (e) {
+        var scale;
+        if (e.originalEvent.wheelDelta > 0 || e.originalEvent.detail < 0) {
+            scale = this.scale + SCROLL_ZOOM_STEP;
+            this._zoom(scale);
+        } else {
+            scale = this.scale - SCROLL_ZOOM_STEP;
+            this._zoom(scale);
+        }
+    },
+    /**
+     * @private
+     * @param {MouseEvent} e
+     */
+    _onStartDrag: function (e) {
+        e.preventDefault();
+        this.enableDrag = true;
+        this.dragStartX = e.clientX - (this.dragstopX || 0);
+        this.dragStartY = e.clientY - (this.dragstopY || 0);
+    },
+    /**
+     * On click of video do not close modal so stop event propagation
+     * and provide play/pause the video instead of quitting it
+     *
+     * @private
+     * @param {MouseEvent} e
+     */
+    _onVideoClicked: function (e) {
+        e.stopPropagation();
+        var videoElement = e.target;
+        if (videoElement.paused) {
+            videoElement.play();
+        } else {
+            videoElement.pause();
+        }
+    },
+    /**
+     * @private
+     * @param {MouseEvent} e
+     */
+    _onZoomIn: function (e) {
+        e.preventDefault();
+        var scale = this.scale + ZOOM_STEP;
+        this._zoom(scale);
+    },
+    /**
+     * @private
+     * @param {MouseEvent} e
+     */
+    _onZoomOut: function (e) {
+        e.preventDefault();
+        var scale = this.scale - ZOOM_STEP;
+        this._zoom(scale);
+    },
+});
+return DocumentViewer;
+});
diff --git a/addons/mail/static/src/js/thread.js b/addons/mail/static/src/js/thread.js
index 038bbf93de9..80d4c4c8a4c 100644
--- a/addons/mail/static/src/js/thread.js
+++ b/addons/mail/static/src/js/thread.js
@@ -2,6 +2,7 @@ odoo.define('mail.ChatThread', function (require) {
 "use strict";
 
 var core = require('web.core');
+var DocumentViewer = require('mail.DocumentViewer');
 var Widget = require('web.Widget');
 
 var QWeb = core.qweb;
@@ -30,6 +31,8 @@ var Thread = Widget.extend({
         "click img": "on_click_redirect",
         "click strong": "on_click_redirect",
         "click .o_thread_show_more": "on_click_show_more",
+        "click .o_attachment_download": "_onAttachmentDownload",
+        "click .o_attachment_view": "_onAttachmentView",
         "click .o_thread_message_needaction": function (event) {
             var message_id = $(event.currentTarget).data('message-id');
             this.trigger("mark_as_read", message_id);
@@ -110,6 +113,8 @@ var Thread = Widget.extend({
             ORDER: ORDER,
         }));
 
+        this.attachments = _.uniq(_.flatten(_.map(messages, 'attachment_ids')));
+
         _.each(msgs, function(msg) {
             var $msg = self.$('.o_thread_message[data-message-id="'+ msg.id +'"]');
             $msg.find('.o_mail_timestamp').data('date', msg.date);
@@ -300,6 +305,29 @@ var Thread = Widget.extend({
     destroy: function () {
         clearInterval(this.update_timestamps_interval);
     },
+
+    //--------------------------------------------------------------------------
+    // Handlers
+    //--------------------------------------------------------------------------
+
+    /**
+     * @private
+     * @param {MouseEvent} event
+     */
+    _onAttachmentDownload: function (event) {
+        event.stopPropagation();
+    },
+    /**
+     * @private
+     * @param {MouseEvent} event
+     */
+    _onAttachmentView: function (event) {
+        var activeAttachmentID = $(event.currentTarget).data('id');
+        if (activeAttachmentID) {
+            var attachmentViewer = new DocumentViewer(this, this.attachments, activeAttachmentID);
+            attachmentViewer.appendTo($('body'));
+        }
+    },
 });
 
 Thread.ORDER = ORDER;
diff --git a/addons/mail/static/src/less/composer.less b/addons/mail/static/src/less/composer.less
index 970d0649aa9..4073cef80c2 100644
--- a/addons/mail/static/src/less/composer.less
+++ b/addons/mail/static/src/less/composer.less
@@ -238,36 +238,60 @@
     100% { background: @odoo-brand-optional }
 }
 
-@o-mail-attachment-image-size: 60px;
+@o-mail-attachment-image-size: 100px;
 .o_attachment {
     position: relative;
-    width: 2*@o-mail-attachment-image-size;
+    vertical-align: top;
     display: inline-block;
-    height: @o-mail-attachment-image-size;
     text-align: center;
-    margin-bottom: 15px;
-
-    .o_image {
-        .o-position-absolute(@top: 0, @left: @o-mail-attachment-image-size/2);
-        width: @o-mail-attachment-image-size;
-        height: @o-mail-attachment-image-size;
+    width: @o-mail-attachment-image-size;
+    margin: 5px;
+    .o_image_box {
+        position: relative;
+        img {
+            width: @o-mail-attachment-image-size;
+            height: @o-mail-attachment-image-size;
+        }
+        .o_image_overlay{
+            display: none;
+        }
+        &:hover .o_image_overlay {
+            display: block;
+            .o-position-absolute(@top: 0, @left: 0, @right:0, @bottom:0);
+            z-index: 20;
+            background: rgba(0, 0, 0, 0.5);
+            overflow: hidden;
+            cursor: pointer;
+            .o_attachment_download {
+                .o-position-absolute(@left: 10px, @bottom:5px);
+            }
+            .o_attachment_play {
+                .o-position-absolute(@top: 50%, @left: 50%);
+                transform: translate(-50%, -50%);
+            }
+            .o_overlay_download {
+                width: 100%;
+                height: 100%;
+            }
+            i {
+                color: #FFFFFF;
+            }
+        }
     }
-
-    .o_attachment_name {
-        display: inline-block;
-        max-width: 100%;
-        margin-top: @o-mail-attachment-image-size;
-        overflow: hidden;
+    .caption {
         text-overflow: ellipsis;
         white-space: nowrap;
-        color: @odoo-main-text-color;
+        overflow: hidden;
+        padding: 5px;
+        a {
+            color: @odoo-main-text-color;
+        }
     }
-
     .o_attachment_progress_bar {
         display: none;
     }
     .o_attachment_delete {
-        .o-position-absolute(@top: 0, @right: 0);
+        .o-position-absolute(@top: -10px, @right: -8px);
         color: @odoo-main-text-color;
         cursor: pointer;
         opacity: 0;
@@ -289,9 +313,76 @@
             display: none;
         }
     }
-
     &:hover .o_attachment_delete {
         opacity: 1;
         .o-transition(opacity, 0.2s, linear);
     }
 }
+
+.o_modal_fullscreen {
+    .o_viewer_content {
+        width: 100%;
+        height: 100%;
+        position: relative;
+        cursor: pointer;
+        .o_viewer-header {
+            width: 100%;
+            height: 45px;
+            padding: 10px 10px 0;
+            background-color: rgba(0, 0, 0, 0.45);
+            cursor: auto;
+            .o_image_caption {
+                color: #FFFFFF;
+                display: inline;
+            }
+        }
+        .o_loading_img {
+            .o-position-absolute(@top: 50%);
+            width: 25px;
+            right: 50%;
+            z-index: 1;
+        }
+        .o_viewer_img_wrapper {
+            width: 100%;
+            height: 100%;
+            position: fixed;
+            .o_viewer_zoomer {
+                width: 100%;
+                height: 100%;
+                .o-flex-display();
+                justify-content: center;
+                align-items: center;
+                img, video {
+                    max-width: 100%;
+                    max-height: 100%;
+                    transition: 0.3s cubic-bezier(0, 0, 0.49, 1.6) 0s, opacity 0.15s;
+                }
+                .o_viewer_video {
+                    height: 80%;
+                }
+            }
+        }
+        .o_viewer_toolbar {
+            .o-position-absolute(@left: 50%);
+            bottom: 15px;
+            transform: translate(-50%, -50%);
+            padding: 8px 10px 0px 10px;
+            background-color: rgba(0, 0, 0, 0.6);
+            border-radius: 4px;
+        }
+    }
+    .arrow {
+        .o-position-absolute(@top: 50%);
+        color: #FFFFFF;
+    }
+    .arrow-left {
+        left: 0;
+    }
+        
+    .arrow-right {
+        right: 0;
+    }
+    i.fa {
+        color: #FFFFFF;
+    }
+}
diff --git a/addons/mail/static/src/less/thread.less b/addons/mail/static/src/less/thread.less
index be39413f573..41512f60b08 100644
--- a/addons/mail/static/src/less/thread.less
+++ b/addons/mail/static/src/less/thread.less
@@ -127,7 +127,6 @@
             }
             img {
                 max-width: 100%;
-                height: auto;
             }
 
             .o_mail_body_long {
diff --git a/addons/mail/static/src/xml/thread.xml b/addons/mail/static/src/xml/thread.xml
index 6f23e4a5e34..43cf896e1cc 100644
--- a/addons/mail/static/src/xml/thread.xml
+++ b/addons/mail/static/src/xml/thread.xml
@@ -18,6 +18,87 @@
         </div>
     </t>
 
+
+    <t t-name="DocumentViewer.Content">
+        <div class="o_viewer_content">
+            <div class="o_viewer-header">
+                <h2 class="o_image_caption"><t t-esc="widget.activeAttachment.name"/></h2>
+                <ul class="list-inline pull-right">
+                    <li t-if="widget.activeAttachment.type == 'image'">
+                        <a class="o_print_btn" href="#">
+                            <i class="fa fa-2x fa-print"/>
+                        </a>
+                    </li>
+                    <li>
+                        <a class="o_close_btn" href="#">
+                            <i class="fa fa-2x fa-times"/>
+                        </a>
+                    </li>
+                </ul>
+            </div>
+            <div class="o_viewer_img_wrapper">
+                <div class="o_viewer_zoomer">
+                    <div t-if="widget.activeAttachment.type == 'image'" class="o_loading_img">
+                        <i class="fa fa-spinner fa-spin fa-3x fa-fw" aria-hidden="true"/>
+                    </div>
+                    <img t-if="widget.activeAttachment.type == 'image'" class="o_viewer_img" t-attf-src="/web/image/#{widget.activeAttachment.id}?unique=1"/>
+                    <video t-if="widget.activeAttachment.type == 'video'" class="o_viewer_video" controls="controls">
+                        <source t-attf-src="/web/image/#{widget.activeAttachment.id}" t-att-data-type="widget.activeAttachment.mimetype"/>
+                    </video>
+                </div>
+            </div>
+            <div t-if="widget.activeAttachment.type == 'image'" class="o_viewer_toolbar">
+                <ul class="list-inline">
+                    <li>
+                        <a class="o_zoom_out" href="#">
+                            <i class="fa fa-2x fa-search-minus"></i>
+                        </a>
+                    </li>
+                    <li>
+                        <a class="o_zoom_in" href="#">
+                            <i class="fa fa-2x fa-search-plus"></i>
+                        </a>
+                    </li>
+                    <li>
+                        <a class="o_download_btn" href="#">
+                            <i class="fa fa-2x fa-download"/>
+                        </a>
+                    </li>
+                </ul>
+            </div>
+        </div>
+    </t>
+
+    <t t-name="DocumentViewer">
+        <div class="modal o_modal_fullscreen" tabindex="-1" role="dialog" aria-hidden="true">
+            <t t-call="DocumentViewer.Content"/>
+            <a class="arrow arrow-left move_previous" href="#">
+                <span class="fa fa-3x fa-chevron-left"/>
+            </a>
+            <a class="arrow arrow-right move_next" href="#">
+                <span class="fa fa-3x fa-chevron-right"/>
+            </a>
+        </div>
+    </t>
+    <t t-name="PrintImage">
+        <html>
+            <head>
+                <script>
+                    function onload_img() {
+                        setTimeout('print_img()', 10);
+                    }
+                    function print_img() {
+                        window.print();
+                        window.close();
+                    }
+                </script>
+            </head>
+            <body onload='onload_img()'>
+                <img t-att-src='src' />
+            </body>
+        </html>
+    </t>
+
     <!-- When a channel is empty-->
     <div t-name="mail.EmptyChannel" class="o_mail_no_content">
         <t t-if="options.channel_id==='channel_inbox'">
@@ -175,10 +256,47 @@
     </t>
 
     <t t-name="mail.Attachment">
+        <t t-set="type" t-value="attachment.mimetype.split('/').shift()"/>
         <div t-attf-class="o_attachment #{attachment.upload ? 'o_attachment_uploading' : ''}" t-att-title="attachment.name">
-            <a class="o_image" t-att-href='attachment.url' target="_blank" t-att-data-mimetype="attachment.mimetype" t-attf-data-src="/web/image/#{attachment.id}/100x80">
-                <span class='o_attachment_name'><t t-esc='attachment.name'/></span>
-            </a>
+            <t t-if="type == 'image'">
+                <div class="o_image_box">
+                    <img t-attf-src="/web/image/#{attachment.id}/200x200/?crop=True"/>
+                    <div t-attf-class="o_image_overlay o_attachment_view"  t-att-data-id="attachment.id">
+                        <a class="o_attachment_download" t-att-href='attachment.url' target="_blank">
+                            <i t-attf-class="fa fa-2x fa-arrow-circle-o-down" title="Download this attachment" aria-hidden="true"></i>
+                        </a>
+                    </div>
+                </div>
+            </t>
+            <t t-elif="type == 'video'">
+                <div class="o_image_box o_image_preview">
+                    <img class="o_image" t-att-data-mimetype="attachment.mimetype"/>
+                    <div t-attf-class="o_image_overlay o_attachment_view"  t-att-data-id="attachment.id">
+                        <a class="o_attachment_play">
+                            <i t-attf-class="fa fa-2x fa-play-circle" title="Play this video" aria-hidden="true"></i>
+                        </a>
+                        <a class="o_attachment_download" t-att-href='attachment.url' target="_blank">
+                            <i t-attf-class="fa fa-2x fa-arrow-circle-o-down" title="Download this attachment" aria-hidden="true"></i>
+                        </a>
+                    </div>
+                </div>
+            </t>
+            <t t-else="">
+                <div class="o_image_box">
+                    <img class="o_image" t-att-data-mimetype="attachment.mimetype"/>
+                    <div t-attf-class="o_image_overlay">
+                        <a class="o_overlay_download" t-att-href='attachment.url' target="_blank"/>
+                        <a class="o_attachment_download" t-att-href='attachment.url' target="_blank">
+                            <i t-attf-class="fa fa-2x fa-arrow-circle-o-down" title="Download this attachment" aria-hidden="true"></i>
+                        </a>
+                    </div>
+                </div>
+            </t>
+            <div class="caption">
+                <a t-att-href='attachment.url' target="_blank">
+                    <t t-esc='attachment.name'/>
+                </a>
+            </div>
             <t t-if="editable">
                 <div class="o_attachment_delete">
                     <i class='fa fa-times-circle' title="Delete this attachment" t-att-data-id="attachment.id"/>
diff --git a/addons/mail/static/tests/chatter_tests.js b/addons/mail/static/tests/chatter_tests.js
index b5d7feab56e..337f3e9f9d1 100644
--- a/addons/mail/static/tests/chatter_tests.js
+++ b/addons/mail/static/tests/chatter_tests.js
@@ -494,6 +494,92 @@ QUnit.test('chatter: post, receive and star messages', function (assert) {
         });
 });
 
+QUnit.test('chatter: Attachment viewer', function (assert) {
+    assert.expect(5);
+    this.data.partner.records[0].message_ids = [1];
+    var messages = [{
+        attachment_ids: [{
+            filename: 'image1.jpg',
+            id:1,
+            mimetype: 'image/jpeg',
+            name: 'Test Image 1',
+            url: '/web/content/1?download=true'
+        },{
+            filename: 'image2.jpg',
+            id:2,
+            mimetype: 'image/jpeg',
+            name: 'Test Image 2',
+            url: '/web/content/2?download=true'
+        },{
+            filename: 'image3.jpg',
+            id:3,
+            mimetype: 'image/jpeg',
+            name: 'Test Image 3',
+            url: '/web/content/3?download=true'
+        }],
+        author_id: ["1", "John Doe"],
+        body: "Attachement viewer test",
+        date: moment("2016-12-20 09:35:40"),
+        displayed_author: "John Doe",
+        id: 1,
+        is_note: false,
+        is_starred: false,
+        model: 'partner',
+        res_id: 2,
+    }];
+    var form = createView({
+        View: FormView,
+        model: 'partner',
+        data: this.data,
+        arch: '<form string="Partners">' +
+                '<sheet>' +
+                    '<field name="foo"/>' +
+                '</sheet>' +
+                '<div class="oe_chatter">' +
+                    '<field name="message_ids" widget="mail_thread" options="{\'display_log_button\': True}"/>' +
+                '</div>' +
+            '</form>',
+        res_id: 2,
+        mockRPC: function (route) {
+            if(_.str.contains(route, '/mail/attachment/preview/')){
+                var canvas = document.createElement('canvas');
+                return $.when(canvas.toDataURL());
+            }
+            return this._super.apply(this, arguments);
+        },
+        intercepts: {
+            get_messages: function (event) {
+                event.stopPropagation();
+                var requested_msgs = _.filter(messages, function (msg) {
+                    return _.contains(event.data.options.ids, msg.id);
+                });
+                event.data.callback($.when(requested_msgs));
+            },
+            get_bus: function (event) {
+                event.stopPropagation();
+                event.data.callback(new Bus());
+            },
+        },
+    });
+    assert.strictEqual(form.$('.o_thread_message .o_attachment').length, 3,
+        "there should be three attachment on message");
+    assert.strictEqual(form.$('.o_thread_message .o_attachment .caption a').first().attr('href'), '/web/content/1?download=true',
+        "image caption should have correct download link");
+    // click on first image attachement
+    form.$('.o_thread_message .o_attachment .o_image_box .o_image_overlay').first().click();
+    assert.strictEqual($('.o_modal_fullscreen img.o_viewer_img[src*="/web/image/1?unique=1"]').length, 1,
+        "Modal popup should open with first image src");
+    //  click on next button
+    $('.modal .arrow.arrow-right.move_next span').click();
+    assert.strictEqual($('.o_modal_fullscreen img.o_viewer_img[src*="/web/image/2?unique=1"]').length, 1,
+        "Modal popup should have now second image src");
+    assert.strictEqual($('.o_modal_fullscreen .o_viewer_toolbar .o_download_btn').length, 1,
+        "Modal popup should have download button");
+    // close attachment popup
+    $('.o_modal_fullscreen .o_viewer-header .o_close_btn').click();
+    form.destroy();
+});
+
 QUnit.test('form activity widget: schedule next activity', function (assert) {
     assert.expect(5);
     this.data.partner.records[0].activity_ids = [1];
diff --git a/addons/mail/views/mail_templates.xml b/addons/mail/views/mail_templates.xml
index 368978bb551..2fe052975c3 100644
--- a/addons/mail/views/mail_templates.xml
+++ b/addons/mail/views/mail_templates.xml
@@ -8,6 +8,7 @@
                 <script type="text/javascript" src="/mail/static/src/js/client_action.js"></script>
                 <script type="text/javascript" src="/mail/static/src/js/chat_window.js"></script>
                 <script type="text/javascript" src="/mail/static/src/js/extended_chat_window.js"></script>
+                <script type="text/javascript" src="/mail/static/src/js/document_viewer.js"></script>
                 <script type="text/javascript" src="/mail/static/src/js/composer.js"></script>
                 <script type="text/javascript" src="/mail/static/src/js/chat_manager.js"></script>
                 <script type="text/javascript" src="/mail/static/src/js/chatter.js"></script>
diff --git a/addons/web/static/src/less/mimetypes.less b/addons/web/static/src/less/mimetypes.less
index 12e86a34ab8..ad0ddbacd81 100644
--- a/addons/web/static/src/less/mimetypes.less
+++ b/addons/web/static/src/less/mimetypes.less
@@ -2,7 +2,7 @@
     background-image: url('/web/static/src/img/mimetypes/unknown.png');
     background-size: contain;
     width: 100px;
-    height: 80px;
+    height: 100px;
     display: inline-block;
     background-position: center;
     background-repeat: no-repeat;
diff --git a/addons/website_livechat/views/website_livechat.xml b/addons/website_livechat/views/website_livechat.xml
index 6aef10b7211..523705d93a9 100644
--- a/addons/website_livechat/views/website_livechat.xml
+++ b/addons/website_livechat/views/website_livechat.xml
@@ -10,6 +10,7 @@
             <xpath expr="." position="inside">
                 <script type="text/javascript" src="/bus/static/src/js/bus.js"></script>
                 <script type="text/javascript" src="/mail/static/src/js/chat_window.js"></script>
+                <script type="text/javascript" src="/mail/static/src/js/document_viewer.js"></script>
                 <script type="text/javascript" src="/mail/static/src/js/thread.js"></script>
                 <script type="text/javascript" src="/im_livechat/static/src/js/im_livechat.js"></script>
                 <link rel="stylesheet" href="/mail/static/src/less/chat_window.less"></link>