Allow accounts without inbox

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

@@ -6469,7 +6469,7 @@ public class AdapterMessage extends RecyclerView.Adapter<AdapterMessage.ViewHold
                                 DB db = DB.getInstance(context);
                                 EntityFolder inbox = db.folder().getFolderByType(account, EntityFolder.INBOX);
 
-                                if (inbox == null)
+                                if (inbox == null || !inbox.selectable)
                                     throw new IllegalArgumentException(context.getString(R.string.title_no_inbox));
 
                                 return inbox;

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

@@ -1019,6 +1019,8 @@ class Core {
             throw new FolderNotFoundException();
         if (folder.id.equals(target.id))
             throw new IllegalArgumentException("self");
+        if (!target.selectable)
+            throw new IllegalArgumentException("not selectable");
 
         // De-classify
         for (EntityMessage message : messages)
@@ -1910,6 +1912,8 @@ class Core {
         Log.i("Delete local count=" + local.size());
         for (String name : local.keySet()) {
             EntityFolder folder = local.get(name);
+            if (EntityFolder.INBOX.equals(name) && !folder.selectable)
+                continue;
             List<EntityFolder> childs = parentFolders.get(name);
             if (EntityFolder.USER.equals(folder.type) ||
                     childs == null || childs.size() == 0) {

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

@@ -679,8 +679,15 @@ public class EmailService implements AutoCloseable {
                 break;
             }
 
-        if (!inbox)
+        if (!inbox) {
-            throw new IllegalArgumentException(context.getString(R.string.title_setup_no_inbox));
+            EntityFolder in = new EntityFolder();
+            in.name = EntityFolder.INBOX;
+            in.type = EntityFolder.INBOX;
+            in.setProperties();
+            in.selectable = false;
+            folders.add(in);
+            //throw new IllegalArgumentException(context.getString(R.string.title_setup_no_inbox));
+        }
 
         return folders;
     }

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

@@ -718,8 +718,15 @@ public class FragmentAccount extends FragmentBase {
 
                     EntityFolder.guessTypes(result.folders, iservice.getStore().getDefaultFolder().getSeparator());
 
-                    if (!inbox)
+                    if (!inbox) {
-                        throw new IllegalArgumentException(context.getString(R.string.title_no_inbox));
+                        EntityFolder in = new EntityFolder();
+                        in.name = EntityFolder.INBOX;
+                        in.type = EntityFolder.INBOX;
+                        in.setProperties();
+                        in.selectable = false;
+                        result.folders.add(in);
+                        //throw new IllegalArgumentException(context.getString(R.string.title_no_inbox));
+                    }
 
                     if (result.folders.size() > 0)
                         Collections.sort(result.folders, result.folders.get(0).getComparator(null));