diff --git a/src/applications/metamta/management/PhabricatorMailManagementVolumeWorkflow.php b/src/applications/metamta/management/PhabricatorMailManagementVolumeWorkflow.php
--- a/src/applications/metamta/management/PhabricatorMailManagementVolumeWorkflow.php
+++ b/src/applications/metamta/management/PhabricatorMailManagementVolumeWorkflow.php
@@ -7,11 +7,18 @@
     $this
       ->setName('volume')
       ->setSynopsis(
-        pht('Show how much mail users have received in the last 30 days.'))
+        pht('Show how much mail users have received in the last n days.'))
       ->setExamples(
         '**volume**')
       ->setArguments(
         array(
+          array(
+            'name'    => 'days',
+            'param'   => 'days',
+            'default' => 30,
+            'help'    => pht(
+              'Number of days back (default 30).'),
+          ),
         ));
   }
 
@@ -19,7 +26,7 @@
     $console = PhutilConsole::getConsole();
     $viewer = $this->getViewer();
 
-    $since = (PhabricatorTime::getNow() - phutil_units('30 days in seconds'));
+    $since = (PhabricatorTime::getNow() - $args->getArg('days') * 86400);
     $until = PhabricatorTime::getNow();
 
     $mails = id(new PhabricatorMetaMTAMailQuery())
@@ -95,7 +102,7 @@
     $table->draw();
 
     echo "\n";
-    echo pht('Mail sent in the last 30 days.')."\n";
+    echo pht('Mail sent in the last %d days.', $args->getArg('days'))."\n";
     echo pht(
       '"Unfiltered" is raw volume before rules applied.')."\n";
     echo pht(