diff --git a/imp/docs/CHANGES b/imp/docs/CHANGES
index ecb69139ef1..cd736526e65 100644
--- a/imp/docs/CHANGES
+++ b/imp/docs/CHANGES
@@ -8,6 +8,7 @@ v6.3.0-git
 v6.2.1
 ------
 
+[mms] Don't perform purge Spam login task unless Spam mailbox exists.
 [mms] Fix dragging a mailbox to the base level in dynamic view.
 [mms] Add ability to drag/drop text to dynamic HTML compose window on Chrome
       and IE.
diff --git a/imp/lib/LoginTasks/Task/PurgeSpam.php b/imp/lib/LoginTasks/Task/PurgeSpam.php
index 01f78c24140..c3970a603c7 100644
--- a/imp/lib/LoginTasks/Task/PurgeSpam.php
+++ b/imp/lib/LoginTasks/Task/PurgeSpam.php
@@ -28,8 +28,11 @@ class IMP_LoginTasks_Task_PurgeSpam extends Horde_LoginTasks_Task
      */
     public function __construct()
     {
-        if ($this->interval = $GLOBALS['prefs']->getValue('purge_spam_interval')) {
-            if ($GLOBALS['prefs']->isLocked('purge_spam_interval')) {
+        global $prefs;
+
+        if (($this->interval = $prefs->getValue('purge_spam_interval')) &&
+            $this->_spamMbox()) {
+            if ($prefs->isLocked('purge_spam_interval')) {
                 $this->display = Horde_LoginTasks::DISPLAY_NONE;
             }
         } else {
@@ -44,9 +47,7 @@ public function __construct()
      */
     public function execute()
     {
-        /* If there is no Spam mailbox set, or it doesn't exist, exit. */
-        if (!($spam = IMP_Mailbox::getPref(IMP_Mailbox::MBOX_SPAM)) ||
-            !$spam->exists) {
+        if (!($spam = $this->_spamMbox())) {
             return false;
         }
 
@@ -83,4 +84,16 @@ public function describe()
                        $GLOBALS['prefs']->getValue('purge_spam_keep'));
     }
 
+    /**
+     * Return the spam mailbox.
+     *
+     * @return IMP_Mailbox  The spam mailbox, if it exists. Otherwise, false.
+     */
+    protected function _spamMbox()
+    {
+        return (($spam = IMP_Mailbox::getPref(IMP_Mailbox::MBOX_SPAM)) && $spam->exists)
+            ? $spam
+            : false;
+    }
+
 }
diff --git a/imp/package.xml b/imp/package.xml
index e7a3d131aa9..1f225bca229 100644
--- a/imp/package.xml
+++ b/imp/package.xml
@@ -3699,6 +3699,7 @@
    <date>2014-07-08</date>
    <license uri="http://www.horde.org/licenses/gpl">GPL-2.0</license>
    <notes>
+* [mms] Don&apos;t perform purge Spam login task unless Spam mailbox exists.
 * [mms] Fix dragging a mailbox to the base level in dynamic view.
 * [mms] Add ability to drag/drop text to dynamic HTML compose window on Chrome and IE.
 * [mms] Re-enable drag/drop of text to dynamic plaintext compose window (Bug #13281).