Why?

app/src/main/java/eu/faircode/email/ServiceSynchronize.java

@@ -341,6 +341,18 @@ public class ServiceSynchronize extends LifecycleService {
         if (unsent > 0)
             builder.setContentText(getResources().getQuantityString(R.plurals.title_notification_unsent, unsent, unsent));
 
+        Intent why = new Intent(Intent.ACTION_VIEW);
+        why.setData(Uri.parse("https://github.com/M66B/open-source-email/blob/master/FAQ.md#FAQ2"));
+        PendingIntent piWhy = PendingIntent.getActivity(this, 0, why, PendingIntent.FLAG_UPDATE_CURRENT);
+
+        Notification.Action.Builder actionWhy = new Notification.Action.Builder(
+                Icon.createWithResource(this, R.drawable.baseline_info_24),
+                getString(R.string.title_notification_why),
+                piWhy);
+
+        if (why.resolveActivity(getPackageManager()) != null)
+            builder.addAction(actionWhy.build());
+
         return builder;
     }
 

app/src/main/res/values/strings.xml

@@ -29,6 +29,7 @@
         <item quantity="other">%1$d unsent messages</item>
     </plurals>
 
+    <string name="title_notification_why">Why?</string>
     <string name="title_notification_failed">\'%1$s\' failed</string>
 
     <string name="menu_setup">Setup</string>