diff --git a/README.md b/README.md
index 78a1dc6..386a02b 100644
--- a/README.md
+++ b/README.md
@@ -1,8 +1,23 @@
 # check_dir_empty
 nagios plugin: check that the directories given are empty
 
-Example:
+## Example
 ~~~
-$ ./check_dir_empty /var/mail
+$ ./check_dir_empty --no-count-empty /var/mail
 OK: All given directories are empty
 ~~~
+
+## Usage
+~~~
+% ./check_dir_empty -h
+usage: check_dir_empty [-h] [--no-count-empty] dir [dir ...]
+
+Check that the directories given are empty
+
+positional arguments:
+ dir               directory to be checked
+
+optional arguments:
+ -h, --help        show this help message and exit
+ --no-count-empty  do not count empty files (useful to check /var/mail)
+~~~
diff --git a/check_dir_empty b/check_dir_empty
index 0e7c189..c565654 100755
--- a/check_dir_empty
+++ b/check_dir_empty
@@ -10,11 +10,19 @@ parser = argparse.ArgumentParser(
 parser.add_argument(
     'directories', metavar='dir', nargs='+', type=str,
     help='directory to be checked')
+parser.add_argument(
+    '--no-count-empty', dest='count_empty', action='store_false',
+    help='do not count empty files (useful to check /var/mail)')
 args = parser.parse_args()
 
 
 for directory in args.directories:
     listdir = os.listdir(directory)
+
+    if not args.count_empty:
+        listdir = [fn for fn in listdir
+                   if os.path.getsize(os.path.join(directory, fn)) > 0]
+
     if len(listdir) != 0:
         print('WARNING: Directory {} is not empty ({} entries)'
               .format(directory, len(listdir)))