diff --git a/apps/kolab_guam/src/rules/kolab_guam_rule_filter_groupware.erl b/apps/kolab_guam/src/rules/kolab_guam_rule_filter_groupware.erl
--- a/apps/kolab_guam/src/rules/kolab_guam_rule_filter_groupware.erl
+++ b/apps/kolab_guam/src/rules/kolab_guam_rule_filter_groupware.erl
@@ -78,15 +78,37 @@
 apply_if_found_kolab(0) -> true;
 apply_if_found_kolab(_) -> false.
 
+% Filter out a would-be empty list of folders, should the list of folders
+% consist of only groupware folders.
+filter_folders(<<>>, State, _, LastChunk) ->
+    { <<>>, State#state{ active = true, last_chunk = LastChunk } };
+
+% Send the response to the client. Note that the last list item is not
+% imploded \r\n in to, so that needs to be added.
+filter_folders(Response, State, More, LastChunk) ->
+    {
+        <<Response/binary, "\r\n">>,
+        State#state { active = More, last_chunk = LastChunk }
+    }.
+
+% The buffer is empty
 filter_folders(<<>>, State) ->
     { <<>>, State#state{ active = true } };
+
+% Parse folders from the buffer, potentially leaving some cruft behind -- the
+% start of the next, incomplete server response line.
 filter_folders(Buffer, #state{ last_chunk = LeftOvers } = State) ->
+    % Add the left overs from the previous buffer to the current buffer
     FullBuffer = <<LeftOvers/binary, Buffer/binary>>,
+    % From that buffer, only take the complete lines and save off the
+    % remainder.
     { FullLinesBuffer, LastChunk } = eimap_utils:only_full_lines(FullBuffer),
+    % Create a list so we can filter the individual folders
     ListResponses = binary:split(FullLinesBuffer, <<"\r\n">>, [ global ]),
     { Response, More } = filter_folders(State, ListResponses, { <<>>, true }),
     %io:format("Filtered ... ~p~n", [Response]),
-    { <<Response/binary, "\r\n">>, State#state { active = More, last_chunk = LastChunk } }.
+    % To send or not to send?
+    filter_folders(Response, State, More, LastChunk).
 
 filter_folders(_State, [], Return) -> Return;
 filter_folders(_State, _Folders, { Acc, false }) -> { Acc, false };