diff --git a/docs/dunst.pod b/docs/dunst.pod
index 76e9833..c9e063e 100644
--- a/docs/dunst.pod
+++ b/docs/dunst.pod
@@ -611,9 +611,9 @@ matched.
 =item B<filtering>
 
 Notifications can be matched for any of the following attributes: appname,
-summary, body, icon, category, match_transient and msg_urgency where each is
-the respective notification attribute to be matched and 'msg_urgency' is the
-urgency of the notification, it is named so to not conflict with trying to
+summary, body, icon, category, match_transient, msg_urgency, and stack_tag where
+each is the respective notification attribute to be matched and 'msg_urgency' is
+the urgency of the notification, it is named so to not conflict with trying to
 modify the urgency.
 
 To define a matching rule simply assign the specified value to the value that
@@ -630,9 +630,9 @@ Shell-like globing is supported.
 =item B<modifying>
 
 The following attributes can be overridden: timeout, urgency, foreground,
-background, frame_color, new_icon, set_transient, format, fullscreen where,
-as with the filtering attributes, each one corresponds to the respective
-notification attribute to be modified.
+background, frame_color, new_icon, set_transient, format, fullscreen,
+set_stack_tag where, as with the filtering attributes, each one corresponds to
+the respective notification attribute to be modified.
 
 As with filtering, to make a rule modify an attribute simply assign it in the
 rule definition.
@@ -640,6 +640,11 @@ rule definition.
 If the format is set to an empty string, the notification will not be
 suppressed.
 
+Notifications with the same non-empty stack_tag value will be stacked
+together. The default stack_stag value is set from the string hints
+"synchronous", "private-synchronous", "x-canonical-private-synchronous", and
+"x-dunst-stack-tag".
+
 =back
 
 =head2 SCRIPTING
diff --git a/dunstrc b/dunstrc
index b3f99fb..bf9fc99 100644
--- a/dunstrc
+++ b/dunstrc
@@ -147,10 +147,10 @@
     # Ignore newlines '\n' in notifications.
     ignore_newline = no
 
-    # Merge multiple notifications with the same content
+    # Stack together notifications with the same content
     stack_duplicates = true
 
-    # Hide the count of merged notifications with the same content
+    # Hide the count of stacked notifications with the same content
     hide_duplicate_count = false
 
     # Display indicators for URLs (U) and actions (A).
@@ -299,7 +299,8 @@
 # override settings for certain messages.
 # Messages can be matched by "appname", "summary", "body", "icon", "category",
 # "msg_urgency" and you can override the "timeout", "urgency", "foreground",
-# "background", "frame_color", "new_icon" and "format", "fullscreen".
+# "background", "frame_color", "new_icon" and "format", "fullscreen",
+# "stack_tag".
 # Shell-like globbing will get expanded.
 #
 # SCRIPTING
@@ -365,4 +366,8 @@
 #    summary = *twitter.com*
 #    urgency = normal
 #
+#[stack-volumes]
+#    appname = "some_volume_notifiers"
+#    set_stack_tag = "volume"
+#
 # vim: ft=cfg
diff --git a/src/dbus.c b/src/dbus.c
index 1e4710d..2330efc 100644
--- a/src/dbus.c
+++ b/src/dbus.c
@@ -65,6 +65,13 @@ static const char *introspection_xml =
     "   </interface>"
     "</node>";
 
+static const char *stack_tag_hints[] = {
+        "synchronous",
+        "private-synchronous",
+        "x-canonical-private-synchronous",
+        "x-dunst-stack-tag"
+};
+
 static void on_get_capabilities(GDBusConnection *connection,
                                 const gchar *sender,
                                 const GVariant *parameters,
@@ -120,6 +127,9 @@ static void on_get_capabilities(GDBusConnection *connection,
         g_variant_builder_add(builder, "s", "body");
         g_variant_builder_add(builder, "s", "body-hyperlinks");
 
+        for (int i = 0; i < sizeof(stack_tag_hints)/sizeof(*stack_tag_hints); ++i)
+                g_variant_builder_add(builder, "s", stack_tag_hints[i]);
+
         if (settings.markup != MARKUP_NO)
                 g_variant_builder_add(builder, "s", "body-markup");
 
@@ -245,6 +255,20 @@ static struct notification *dbus_message_to_notification(const gchar *sender, GV
                                                 n->progress = g_variant_get_uint32(dict_value);
                                                 g_variant_unref(dict_value);
                                         }
+
+                                        /* Check for hints that define the stack_tag
+                                         *
+                                         * Only accept to first one we find.
+                                         */
+                                        for (int i = 0; i < sizeof(stack_tag_hints)/sizeof(*stack_tag_hints); ++i) {
+                                                dict_value = g_variant_lookup_value(content, stack_tag_hints[i], G_VARIANT_TYPE_STRING);
+                                                if (dict_value) {
+                                                        n->stack_tag = g_variant_dup_string(dict_value, NULL);
+                                                        g_variant_unref(dict_value);
+                                                        break;
+                                                }
+                                        }
+
                                 }
                                 break;
                         case 7:
diff --git a/src/notification.c b/src/notification.c
index e8699c8..0155093 100644
--- a/src/notification.c
+++ b/src/notification.c
@@ -66,6 +66,7 @@ void notification_print(const struct notification *n)
         printf("\tframe: %s\n", n->colors[ColFrame]);
         printf("\tfullscreen: %s\n", enum_to_string_fullscreen(n->fullscreen));
         printf("\tprogress: %d\n", n->progress);
+        printf("\tstack_tag: %s\n", (n->stack_tag ? n->stack_tag : ""));
         printf("\tid: %d\n", n->id);
         if (n->urls) {
                 char *urls = string_replace_all("\n", "\t\t\n", g_strdup(n->urls));
@@ -251,6 +252,7 @@ void notification_unref(struct notification *n)
         g_free(n->colors[ColFG]);
         g_free(n->colors[ColBG]);
         g_free(n->colors[ColFrame]);
+        g_free(n->stack_tag);
 
         actions_free(n->actions);
         rawimage_free(n->raw_icon);
diff --git a/src/notification.h b/src/notification.h
index ffc887b..185232d 100644
--- a/src/notification.h
+++ b/src/notification.h
@@ -70,6 +70,8 @@ struct notification {
         const char *script;
         char *colors[3];
 
+        char *stack_tag;    /**< stack notifications by tag */
+
         /* Hints */
         bool transient;     /**< timeout albeit user is idle */
         int progress;       /**< percentage (-1: undefined) */
diff --git a/src/queues.c b/src/queues.c
index efa28af..c90faf2 100644
--- a/src/queues.c
+++ b/src/queues.c
@@ -34,6 +34,7 @@ int next_notification_id = 1;
 bool pause_displayed = false;
 
 static bool queues_stack_duplicate(struct notification *n);
+static bool queues_stack_by_tag(struct notification *n);
 
 /* see queues.h */
 void queues_init(void)
@@ -123,6 +124,7 @@ static bool queues_notification_is_ready(const struct notification *n, bool full
 /* see queues.h */
 int queues_notification_insert(struct notification *n)
 {
+        bool inserted = false;
 
         /* do not display the message, if the message is empty */
         if (STR_EMPTY(n->msg)) {
@@ -146,14 +148,17 @@ int queues_notification_insert(struct notification *n)
                 return 0;
         }
 
-        if (n->id == 0) {
+        if (!inserted && n->id != 0 && queues_notification_replace_id(n))
+                inserted = true;
+        else
                 n->id = ++next_notification_id;
-                if (!settings.stack_duplicates || !queues_stack_duplicate(n))
-                        g_queue_insert_sorted(waiting, n, notification_cmp_data, NULL);
-        } else {
-                if (!queues_notification_replace_id(n))
-                        g_queue_insert_sorted(waiting, n, notification_cmp_data, NULL);
-        }
+
+        if (!inserted && STR_FULL(n->stack_tag) && queues_stack_by_tag(n))
+                inserted = true;
+        if (!inserted && settings.stack_duplicates && queues_stack_duplicate(n))
+                inserted = true;
+        if (!inserted)
+                g_queue_insert_sorted(waiting, n, notification_cmp_data, NULL);
 
         if (settings.print_notifications)
                 notification_print(n);
@@ -170,7 +175,7 @@ int queues_notification_insert(struct notification *n)
 static bool queues_stack_duplicate(struct notification *n)
 {
         GQueue *allqueues[] = { displayed, waiting };
-        for (int i = 0; i < sizeof(allqueues)/sizeof(GList*); i++) {
+        for (int i = 0; i < sizeof(allqueues)/sizeof(GQueue*); i++) {
                 for (GList *iter = g_queue_peek_head_link(allqueues[i]); iter;
                      iter = iter->next) {
                         struct notification *orig = iter->data;
@@ -188,7 +193,7 @@ static bool queues_stack_duplicate(struct notification *n)
                                 n->dup_count = orig->dup_count;
                                 signal_notification_closed(orig, 1);
 
-                                if ( allqueues[i] == displayed )
+                                if (allqueues[i] == displayed)
                                         n->start = time_monotonic_now();
 
                                 notification_unref(orig);
@@ -200,11 +205,43 @@ static bool queues_stack_duplicate(struct notification *n)
         return false;
 }
 
+/**
+ * Replaces the first notification of the same stack_tag
+ *
+ * @return true, if notification got stacked
+ * @return false, if notification did not get stacked
+ */
+static bool queues_stack_by_tag(struct notification *new)
+{
+        GQueue *allqueues[] = { displayed, waiting };
+        for (int i = 0; i < sizeof(allqueues)/sizeof(GQueue*); i++) {
+                for (GList *iter = g_queue_peek_head_link(allqueues[i]); iter;
+                            iter = iter->next) {
+                        struct notification *old = iter->data;
+                        if (STR_FULL(old->stack_tag) && STR_EQ(old->stack_tag, new->stack_tag)) {
+                                iter->data = new;
+                                new->dup_count = old->dup_count;
+
+                                signal_notification_closed(old, 1);
+
+                                if (allqueues[i] == displayed) {
+                                        new->start = time_monotonic_now();
+                                        notification_run_script(new);
+                                }
+
+                                notification_unref(old);
+                                return true;
+                        }
+                }
+        }
+        return false;
+}
+
 /* see queues.h */
 bool queues_notification_replace_id(struct notification *new)
 {
         GQueue *allqueues[] = { displayed, waiting };
-        for (int i = 0; i < sizeof(allqueues)/sizeof(GList*); i++) {
+        for (int i = 0; i < sizeof(allqueues)/sizeof(GQueue*); i++) {
                 for (GList *iter = g_queue_peek_head_link(allqueues[i]);
                             iter;
                             iter = iter->next) {
@@ -213,7 +250,7 @@ bool queues_notification_replace_id(struct notification *new)
                                 iter->data = new;
                                 new->dup_count = old->dup_count;
 
-                                if ( allqueues[i] == displayed ) {
+                                if (allqueues[i] == displayed) {
                                         new->start = time_monotonic_now();
                                         notification_run_script(new);
                                 }
@@ -232,7 +269,7 @@ void queues_notification_close_id(int id, enum reason reason)
         struct notification *target = NULL;
 
         GQueue *allqueues[] = { displayed, waiting };
-        for (int i = 0; i < sizeof(allqueues)/sizeof(GList*); i++) {
+        for (int i = 0; i < sizeof(allqueues)/sizeof(GQueue*); i++) {
                 for (GList *iter = g_queue_peek_head_link(allqueues[i]); iter;
                      iter = iter->next) {
                         struct notification *n = iter->data;
diff --git a/src/rules.c b/src/rules.c
index 4f13977..104b4f2 100644
--- a/src/rules.c
+++ b/src/rules.c
@@ -47,6 +47,10 @@ void rule_apply(struct rule *r, struct notification *n)
                 n->format = r->format;
         if (r->script)
                 n->script = r->script;
+        if (r->set_stack_tag) {
+                g_free(n->stack_tag);
+                n->stack_tag = g_strdup(r->set_stack_tag);
+        }
 }
 
 /*
@@ -73,6 +77,7 @@ void rule_init(struct rule *r)
         r->body = NULL;
         r->icon = NULL;
         r->category = NULL;
+        r->stack_tag = NULL;
         r->msg_urgency = URG_NONE;
         r->timeout = -1;
         r->urgency = URG_NONE;
@@ -86,6 +91,7 @@ void rule_init(struct rule *r)
         r->bg = NULL;
         r->fc = NULL;
         r->format = NULL;
+        r->set_stack_tag = NULL;
 }
 
 /*
@@ -93,11 +99,12 @@ void rule_init(struct rule *r)
  */
 bool rule_matches_notification(struct rule *r, struct notification *n)
 {
-        return   ( (!r->appname  || (n->appname  && !fnmatch(r->appname,  n->appname, 0)))
-                && (!r->summary  || (n->summary  && !fnmatch(r->summary,  n->summary, 0)))
-                && (!r->body     || (n->body     && !fnmatch(r->body,     n->body, 0)))
-                && (!r->icon     || (n->icon     && !fnmatch(r->icon,     n->icon, 0)))
-                && (!r->category || (n->category && !fnmatch(r->category, n->category, 0)))
+        return   ( (!r->appname   || (n->appname   && !fnmatch(r->appname,   n->appname, 0)))
+                && (!r->summary   || (n->summary   && !fnmatch(r->summary,   n->summary, 0)))
+                && (!r->body      || (n->body      && !fnmatch(r->body,      n->body, 0)))
+                && (!r->icon      || (n->icon      && !fnmatch(r->icon,      n->icon, 0)))
+                && (!r->category  || (n->category  && !fnmatch(r->category,  n->category, 0)))
+                && (!r->stack_tag || (n->stack_tag && !fnmatch(r->stack_tag, n->stack_tag, 0)))
                 && (r->match_transient == -1 || (r->match_transient == n->transient))
                 && (r->msg_urgency == URG_NONE || r->msg_urgency == n->urgency));
 }
diff --git a/src/rules.h b/src/rules.h
index 3ab82be..df45f5d 100644
--- a/src/rules.h
+++ b/src/rules.h
@@ -16,6 +16,7 @@ struct rule {
         char *body;
         char *icon;
         char *category;
+        char *stack_tag;
         int msg_urgency;
 
         /* actions */
@@ -32,6 +33,7 @@ struct rule {
         const char *format;
         const char *script;
         enum behavior_fullscreen fullscreen;
+        char *set_stack_tag;
 };
 
 extern GSList *rules;
diff --git a/src/settings.c b/src/settings.c
index a71978f..c27cc4b 100644
--- a/src/settings.c
+++ b/src/settings.c
@@ -368,7 +368,7 @@ void load_settings(char *cmdline_config_path)
         settings.hide_duplicate_count = option_get_bool(
                 "global",
                 "hide_duplicate_count", "-hide_duplicate_count", false,
-                "Hide the count of merged notifications with the same content"
+                "Hide the count of stacked notifications with the same content"
         );
 
         settings.sticky_history = option_get_bool(
@@ -444,7 +444,7 @@ void load_settings(char *cmdline_config_path)
         settings.stack_duplicates = option_get_bool(
                 "global",
                 "stack_duplicates", "-stack_duplicates", true,
-                "Merge multiple notifications with the same content"
+                "Stack together notifications with the same content"
         );
 
         settings.startup_notification = option_get_bool(
@@ -785,6 +785,7 @@ void load_settings(char *cmdline_config_path)
                 r->body = ini_get_string(cur_section, "body", r->body);
                 r->icon = ini_get_string(cur_section, "icon", r->icon);
                 r->category = ini_get_string(cur_section, "category", r->category);
+                r->stack_tag = ini_get_string(cur_section, "stack_tag", r->stack_tag);
                 r->timeout = ini_get_time(cur_section, "timeout", r->timeout);
 
                 {
@@ -819,6 +820,7 @@ void load_settings(char *cmdline_config_path)
                         g_free(c);
                 }
                 r->script = ini_get_path(cur_section, "script", NULL);
+                r->set_stack_tag = ini_get_string(cur_section, "set_stack_tag", r->set_stack_tag);
         }
 
 #ifndef STATIC_CONFIG