diff -ur munin-2.0.42.orig/plugins/node.d/postfix_mailqueue.in munin-2.0.42/plugins/node.d/postfix_mailqueue.in
--- munin-2.0.42.orig/plugins/node.d/postfix_mailqueue.in	2018-09-21 05:11:11.000000000 +0300
+++ munin-2.0.42/plugins/node.d/postfix_mailqueue.in	2018-09-30 13:33:21.825373214 +0300
@@ -103,7 +103,7 @@
         cat <<'EOF'
 graph_title Postfix Mailqueue
 graph_vlabel Mails in queue
-graph_category postfix
+graph_category mail
 graph_total Total
 active.label active
 deferred.label deferred
diff -ur munin-2.0.42.orig/plugins/node.d/postfix_mailstats.in munin-2.0.42/plugins/node.d/postfix_mailstats.in
--- munin-2.0.42.orig/plugins/node.d/postfix_mailstats.in	2018-09-21 05:11:11.000000000 +0300
+++ munin-2.0.42/plugins/node.d/postfix_mailstats.in	2018-09-30 13:33:14.492320072 +0300
@@ -141,7 +141,7 @@
     print "graph_vlabel mails / \${graph_period}\n";
     print "graph_scale  no\n";
     print "graph_total  Total\n";
-    print "graph_category postfix\n";
+    print "graph_category mail\n";
     print "graph_period minute\n";
     print "delivered.label delivered\n";
     print "delivered.type DERIVE\n";
diff -ur munin-2.0.42.orig/plugins/node.d/postfix_mailvolume.in munin-2.0.42/plugins/node.d/postfix_mailvolume.in
--- munin-2.0.42.orig/plugins/node.d/postfix_mailvolume.in	2018-09-21 05:11:11.000000000 +0300
+++ munin-2.0.42/plugins/node.d/postfix_mailvolume.in	2018-09-30 13:33:06.602262890 +0300
@@ -133,7 +133,7 @@
     print "graph_args --base 1000 -l 0\n";
     print "graph_vlabel bytes / \${graph_period}\n";
     print "graph_scale yes\n";
-    print "graph_category postfix\n";
+    print "graph_category mail\n";
     print "volume.label delivered volume\n";
     print "volume.type DERIVE\n";
     print "volume.min 0\n";