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
@@ -77,6 +77,9 @@
 apply_if_found_kolab(0) -> true;
 apply_if_found_kolab(_) -> false.
 
+possibly_append_newline(<<>>) -> <<>> ;
+possibly_append_newline(Response) -> <<Response/binary, "\r\n">> .
+
 filter_folders(<<>>, State) ->
     { <<>>, State#state{ active = true } };
 filter_folders(Buffer, #state{ last_chunk = LeftOvers } = State) ->
@@ -85,7 +88,7 @@
     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 } }.
+    { possibly_append_newline(Response), State#state { active = More, last_chunk = LastChunk } }.
 
 filter_folders(_State, [], Return) -> Return;
 filter_folders(_State, _Folders, { Acc, false }) -> { Acc, false };
diff --git a/apps/kolab_guam/test/kolab_guam_rules_SUITE.erl b/apps/kolab_guam/test/kolab_guam_rules_SUITE.erl
--- a/apps/kolab_guam/test/kolab_guam_rules_SUITE.erl
+++ b/apps/kolab_guam/test/kolab_guam_rules_SUITE.erl
@@ -113,6 +113,17 @@
                 <<"\"/\" Notes\r\n* LIST (\\Subscribed) \"/\" Sent\r\n* LIST (\\Subscribed) \"/\" Spam\r\n* LIST (\\Subscribed) \"/\" Tasks\r\n* LIST (\\Subscribed) \"/\" Trash\r\n7 OK Completed (0.000 secs 15 calls)\r\n">>
             ],
             <<"* LIST (\\Noinferiors \\Subscribed) \"/\" INBOX\r\n* LIST (\\Subscribed) \"/\" Archive\r\n* LIST (\\Subscribed) \"/\" Drafts\r\n* LIST (\\Subscribed) \"/\" Sent\r\n* LIST (\\Subscribed) \"/\" Spam\r\n* LIST (\\Subscribed) \"/\" Trash\r\n7 OK Completed (0.000 secs 15 calls)\r\n">>
+        },
+        %Filter complete packet
+        {
+            [
+             {<<"Calendar">>, <<"Calendar/">>}
+            ],
+            [
+                <<"* LIST (\\Subscribed \\HasChildren) \"/\" Calendar\r\n">>,
+                <<"7 OK Completed (0.000 secs 15 calls)\r\n">>
+            ],
+            <<"7 OK Completed (0.000 secs 15 calls)\r\n">>
         }
     ],
     %% setup boilerplate