diff --git a/calendar/gui/dialogs/cal-prefs-dialog.c b/calendar/gui/dialogs/cal-prefs-dialog.c
index fafa308..04bd116 100644
--- a/calendar/gui/dialogs/cal-prefs-dialog.c
+++ b/calendar/gui/dialogs/cal-prefs-dialog.c
@@ -103,7 +103,8 @@ update_day_second_zone_caption (CalendarPrefsDialog *prefs)
 
 	g_return_if_fail (prefs != NULL);
 
-	caption = _("None");
+	/* Translators: "None" indicates no second time zone set for a day view */
+	caption = C_("cal-second-zone", "None");
 
 	location = calendar_config_get_day_second_zone ();
 	if (location && *location) {
@@ -152,7 +153,7 @@ day_second_zone_clicked (GtkWidget *widget, CalendarPrefsDialog *prefs)
 	g_free (location);
 
 	group = NULL;
-	item = gtk_radio_menu_item_new_with_label (group, _("None"));
+	item = gtk_radio_menu_item_new_with_label (group, C_("cal-second-zone", "None"));
 	group = gtk_radio_menu_item_get_group (GTK_RADIO_MENU_ITEM (item));
 	if (!second_zone)
 		gtk_check_menu_item_set_active (GTK_CHECK_MENU_ITEM (item), TRUE);
diff --git a/calendar/gui/dialogs/cal-prefs-dialog.ui b/calendar/gui/dialogs/cal-prefs-dialog.ui
index be78a8f..d3478a2 100644
--- a/calendar/gui/dialogs/cal-prefs-dialog.ui
+++ b/calendar/gui/dialogs/cal-prefs-dialog.ui
@@ -188,7 +188,7 @@
                     <property name="visible">True</property>
                     <child>
                       <object class="GtkButton" id="day_second_zone">
-                        <property name="label" translatable="yes">None</property>
+                        <property name="label" translatable="yes" context="cal-second-zone">None</property>
                         <property name="visible">True</property>
                         <property name="can_focus">True</property>
                         <property name="receives_default">False</property>
diff --git a/calendar/gui/dialogs/event-page.c b/calendar/gui/dialogs/event-page.c
index f47ce3a..61ebb08 100644
--- a/calendar/gui/dialogs/event-page.c
+++ b/calendar/gui/dialogs/event-page.c
@@ -2937,7 +2937,8 @@ init_widgets (EventPage *epage)
 	}
 
 	gtk_combo_box_append_text (GTK_COMBO_BOX (priv->alarm_time_combo), _("Customize"));
-	gtk_combo_box_prepend_text (GTK_COMBO_BOX (priv->alarm_time_combo), _("None"));
+	/* Translators: "None" for "No alarm set" */
+	gtk_combo_box_prepend_text (GTK_COMBO_BOX (priv->alarm_time_combo), C_("cal-alarms", "None"));
 
 	g_signal_connect_swapped (
 		priv->alarm_time_combo, "changed",
diff --git a/calendar/gui/e-cal-model-tasks.c b/calendar/gui/e-cal-model-tasks.c
index f189ac2..2e80975 100644
--- a/calendar/gui/e-cal-model-tasks.c
+++ b/calendar/gui/e-cal-model-tasks.c
@@ -724,7 +724,11 @@ set_status (ECalModelComponent *comp_data, const gchar *value)
 	prop = icalcomponent_get_first_property (comp_data->icalcomp, ICAL_STATUS_PROPERTY);
 
 	/* an empty string is the same as 'None' */
-	if (!value[0] || !e_util_utf8_strcasecmp (value, _("None")))
+	if (!value[0])
+		return;
+
+	/* Translators: "None" for task's status */
+	if (!e_util_utf8_strcasecmp (value, C_("cal-task-status", "None")))
 		return;
 	else if (!e_util_utf8_strcasecmp (value, _("Not Started")))
 		status = ICAL_STATUS_NEEDSACTION;
diff --git a/calendar/gui/e-day-view-time-item.c b/calendar/gui/e-day-view-time-item.c
index ff0f640..0e7fdfb 100644
--- a/calendar/gui/e-day-view-time-item.c
+++ b/calendar/gui/e-day-view-time-item.c
@@ -795,7 +795,7 @@ e_day_view_time_item_show_popup_menu (EDayViewTimeItem *time_item,
 	gtk_menu_shell_append (GTK_MENU_SHELL (submenu), item);
 
 	group = NULL;
-	item = gtk_radio_menu_item_new_with_label (group, _("None"));
+	item = gtk_radio_menu_item_new_with_label (group, C_("cal-second-zone", "None"));
 	group = gtk_radio_menu_item_get_group (GTK_RADIO_MENU_ITEM (item));
 	if (!time_item->priv->second_zone)
 		gtk_check_menu_item_set_active (GTK_CHECK_MENU_ITEM (item), TRUE);
diff --git a/calendar/gui/e-itip-control.c b/calendar/gui/e-itip-control.c
index a91812c..44ac221 100644
--- a/calendar/gui/e-itip-control.c
+++ b/calendar/gui/e-itip-control.c
@@ -1144,7 +1144,8 @@ write_html (EItipControl *itip, const gchar *itip_desc, const gchar *itip_title,
 
 	/* Summary */
 	e_cal_component_get_summary (priv->comp, &text);
-	str = g_strdup_printf ("<i>%s:</i>", _("None"));
+	/* Translators: "None" used as a default value for events without Summary received by mail */
+	str = g_strdup_printf ("<i>%s</i>", C_("cal-itip", "None"));
 
 	html = text.value ? e_text_to_html_full (text.value, E_TEXT_TO_HTML_CONVERT_NL, 0) : str;
 	g_string_append_printf (
diff --git a/filter/e-filter-rule.c b/filter/e-filter-rule.c
index f1ecf49..6bd5095 100644
--- a/filter/e-filter-rule.c
+++ b/filter/e-filter-rule.c
@@ -741,6 +741,7 @@ filter_rule_get_widget (EFilterRule *rule,
 	}
 
 	if (context->flags & E_RULE_CONTEXT_THREADING) {
+		/* Translators: "None" for not including threads; part of "Include threads: None" */
 		const gchar *thread_types[] = { N_("None"), N_("All related"), N_("Replies"), N_("Replies and parents"), N_("No reply or parent") };
 
 		label = gtk_label_new_with_mnemonic (_("I_nclude threads"));
diff --git a/mail/em-account-editor.c b/mail/em-account-editor.c
index 791e9da..4752acc 100644
--- a/mail/em-account-editor.c
+++ b/mail/em-account-editor.c
@@ -862,7 +862,8 @@ emae_setup_signatures (EMAccountEditor *emae, GtkBuilder *builder)
 	store = gtk_list_store_new (2, G_TYPE_STRING, G_TYPE_STRING);
 
 	gtk_list_store_append (store, &iter);
-	gtk_list_store_set (store, &iter, 0, _("None"), 1, NULL, -1);
+	/* Translators: "None" as an option for a default signature of an account, part of "Signature: None" */
+	gtk_list_store_set (store, &iter, 0, C_("mail-signature", "None"), 1, NULL, -1);
 
 	signatures = e_get_signature_list ();
 
@@ -1678,7 +1679,8 @@ emae_refresh_providers (EMAccountEditor *emae, EMAccountEditorService *service)
 	/* We just special case each type here, its just easier */
 	if (service->type == CAMEL_PROVIDER_STORE) {
 		gtk_list_store_append (store, &iter);
-		gtk_list_store_set (store, &iter, 0, _("None"), 1, NULL, -1);
+		/* Translators: "None" for receiving account type, beside of IMAP, POP3, ... */
+		gtk_list_store_set (store, &iter, 0, C_("mail-receiving", "None"), 1, NULL, -1);
 		i++;
 	}
 
diff --git a/modules/mail/e-mail-junk-hook.c b/modules/mail/e-mail-junk-hook.c
index ccdcf0c..bf4a5cc 100644
--- a/modules/mail/e-mail-junk-hook.c
+++ b/modules/mail/e-mail-junk-hook.c
@@ -84,8 +84,10 @@ mail_junk_hook_get_name (CamelJunkPlugin *junk_plugin)
 
 	interface = (EMJunkInterface *) junk_plugin;
 
-	if (!interface->hook->plugin->enabled)
-		return _("None");
+	if (!interface->hook->plugin->enabled) {
+		/* Translators: "None" for a junk hook name, when the junk plugin is not enabled */
+		return C_("mail-junk-hook", "None");
+	}
 
 	return interface->hook->plugin->name;
 }
diff --git a/plugins/calendar-weather/calendar-weather.c b/plugins/calendar-weather/calendar-weather.c
index b558f7e..ad2c273 100644
--- a/plugins/calendar-weather/calendar-weather.c
+++ b/plugins/calendar-weather/calendar-weather.c
@@ -321,7 +321,8 @@ location_clicked (GtkButton *button, ESource *source)
 
 		label = GTK_WIDGET (gtk_bin_get_child (GTK_BIN (button)));
 		text = gtk_label_get_text (GTK_LABEL (label));
-		if (strcmp ((const gchar *)text, _("None")) == 0)
+		/* Translators: "None" location for a weather calendar */
+		if (strcmp ((const gchar *)text, C_("weather-cal-location", "None")) == 0)
 			e_source_set_relative_uri (source, "");
 	}
 
@@ -374,8 +375,9 @@ e_calendar_weather_location (EPlugin *epl, EConfigHookItemFactoryData *data)
 		gchar *location = build_location_path (iter);
 		text = gtk_label_new (location);
 		g_free (location);
-	} else
-		text = gtk_label_new (_("None"));
+	} else {
+		text = gtk_label_new (C_("weather-cal-location", "None"));
+	}
 	gtk_widget_show (text);
 	gtk_label_set_ellipsize (GTK_LABEL (text), PANGO_ELLIPSIZE_START);
 	gtk_container_add (GTK_CONTAINER (button), text);
diff --git a/plugins/email-custom-header/email-custom-header.c b/plugins/email-custom-header/email-custom-header.c
index a4e1ef2..ad9310d 100644
--- a/plugins/email-custom-header/email-custom-header.c
+++ b/plugins/email-custom-header/email-custom-header.c
@@ -376,7 +376,9 @@ epech_setup_widgets (CustomHeaderOptionsDialog *mch)
 				str);
 		}
 
-		gtk_combo_box_append_text (GTK_COMBO_BOX (sub_combo_box_ptr->header_value_combo_box), _("None"));
+		/* Translators: "None" as an email custom header option in a dialog invoked by Insert->Custom Header from Composer,
+		   indicating the header will not be added to a mail message */
+		gtk_combo_box_append_text (GTK_COMBO_BOX (sub_combo_box_ptr->header_value_combo_box), C_("email-custom-header", "None"));
 		gtk_widget_show (sub_combo_box_ptr->header_value_combo_box);
 	}
 }
diff --git a/plugins/itip-formatter/itip-formatter.c b/plugins/itip-formatter/itip-formatter.c
index 4ce4b43..7f03570 100644
--- a/plugins/itip-formatter/itip-formatter.c
+++ b/plugins/itip-formatter/itip-formatter.c
@@ -2298,7 +2298,7 @@ format_itip_object (EMFormatHTML *efh, GtkHTMLEmbedded *eb, EMFormatHTMLPObject
 	}
 
 	e_cal_component_get_summary (info->comp, &text);
-	itip_view_set_summary (ITIP_VIEW (info->view), text.value ? text.value : _("None"));
+	itip_view_set_summary (ITIP_VIEW (info->view), text.value ? text.value : C_("cal-itip", "None"));
 
 	e_cal_component_get_location (info->comp, &string);
 	itip_view_set_location (ITIP_VIEW (info->view), string);
diff --git a/widgets/misc/e-account-tree-view.c b/widgets/misc/e-account-tree-view.c
index 8e57dfc..8c2e210 100644
--- a/widgets/misc/e-account-tree-view.c
+++ b/widgets/misc/e-account-tree-view.c
@@ -121,7 +121,7 @@ account_tree_view_refresh_cb (EAccountList *account_list,
 		if (url != NULL && url->protocol != NULL)
 			protocol = url->protocol;
 		else
-			protocol = _("None");
+			protocol = C_("mail-receiving", "None");
 
 		gtk_list_store_append (store, &tree_iter);
 		gtk_list_store_set (
diff --git a/widgets/misc/e-dateedit.c b/widgets/misc/e-dateedit.c
index 03af596..975018e 100644
--- a/widgets/misc/e-dateedit.c
+++ b/widgets/misc/e-dateedit.c
@@ -1674,7 +1674,8 @@ field_set_to_none (const gchar *text)
 	while (n = (gint)((guchar)*pos), isspace (n))
 		pos++;
 
-	none_string = _("None");
+	/* Translators: "None" for date field of a date edit, shown when there is no date set */
+	none_string = C_("date", "None");
 
 	if (*pos == '\0' || !strncmp (pos, none_string, strlen (none_string)))
 		return TRUE;
@@ -1891,7 +1892,7 @@ e_date_edit_update_date_entry		(EDateEdit	*dedit)
 	priv = dedit->priv;
 
 	if (priv->date_set_to_none || !priv->date_is_valid) {
-		gtk_entry_set_text (GTK_ENTRY (priv->date_entry), _("None"));
+		gtk_entry_set_text (GTK_ENTRY (priv->date_entry), C_("date", "None"));
 	} else {
 		/* This is a strftime() format for a short date.
 		   %x the preferred date representation for the current locale without the time,
diff --git a/widgets/misc/e-send-options.ui b/widgets/misc/e-send-options.ui
index d02393b..c5911d4 100644
--- a/widgets/misc/e-send-options.ui
+++ b/widgets/misc/e-send-options.ui
@@ -66,7 +66,7 @@
     </columns>
     <data>
       <row>
-        <col id="0" translatable="yes">None</col>
+        <col id="0" translatable="yes" context="send-options" comments="Translators: Used in send options dialog">None</col>
       </row>
       <row>
         <col id="0" translatable="yes">Mail Receipt</col>
@@ -79,7 +79,7 @@
     </columns>
     <data>
       <row>
-        <col id="0" translatable="yes">None</col>
+        <col id="0" translatable="yes" context="send-options">None</col>
       </row>
       <row>
         <col id="0" translatable="yes">Mail Receipt</col>
@@ -92,7 +92,7 @@
     </columns>
     <data>
       <row>
-        <col id="0" translatable="yes">None</col>
+        <col id="0" translatable="yes" context="send-options">None</col>
       </row>
       <row>
         <col id="0" translatable="yes">Mail Receipt</col>
@@ -105,7 +105,7 @@
     </columns>
     <data>
       <row>
-        <col id="0" translatable="yes">None</col>
+        <col id="0" translatable="yes" context="send-options">None</col>
       </row>
       <row>
         <col id="0" translatable="yes">Mail Receipt</col>
diff --git a/widgets/misc/e-signature-combo-box.c b/widgets/misc/e-signature-combo-box.c
index fe4e474..a70c9cc 100644
--- a/widgets/misc/e-signature-combo-box.c
+++ b/widgets/misc/e-signature-combo-box.c
@@ -72,7 +72,7 @@ signature_combo_box_refresh_cb (ESignatureList *signature_list,
 	gtk_list_store_append (store, &tree_iter);
 	gtk_list_store_set (
 		store, &tree_iter,
-		COLUMN_STRING, _("None"),
+		COLUMN_STRING, C_("mail-signature", "None"),
 		COLUMN_SIGNATURE, NULL, -1);
 
 	if (signature_list == NULL)
diff --git a/widgets/table/e-cell-date-edit.c b/widgets/table/e-cell-date-edit.c
index 1848b28..ab580cd 100644
--- a/widgets/table/e-cell-date-edit.c
+++ b/widgets/table/e-cell-date-edit.c
@@ -309,7 +309,8 @@ e_cell_date_edit_init (ECellDateEdit *ecde)
 			    ecde);
 	ecde->today_button = today_button;
 
-	none_button = gtk_button_new_with_label (_("None"));
+	/* Translators: "None" as a label of a button to unset date in a date table cell */
+	none_button = gtk_button_new_with_label (C_("table-date", "None"));
 	gtk_container_add (GTK_CONTAINER (bbox), none_button);
         gtk_widget_show (none_button);
 	g_signal_connect((none_button), "clicked",
