diff -ruN original/mailchimp.module mod/mailchimp.module
--- original/mailchimp.module	2011-04-28 01:13:47.000000000 +0700
+++ mod/mailchimp.module	2011-06-18 17:33:38.000000000 +0700
@@ -55,7 +55,7 @@
         // include interest groups
         if (isset($edit['interest_groups_' . $list->id]) && is_array($edit['interest_groups_' . $list->id])) {
           foreach($edit['interest_groups_' . $list->id] as $key => $group) {
-            $merge_vars['GROUPINGS'][] = array('id' => $key, 'groups' => is_array($group) ? implode(', ', array_filter($group)) : $group);
+            $merge_vars['GROUPINGS'][] = array('id' => $key, 'groups' => $q->implodeInterestGroups($group));
           }
         }
   
@@ -296,7 +296,7 @@
           // include interest groups
           if (isset($form_state['values']['interest_groups_' . $list->id]) && is_array($form_state['values']['interest_groups_' . $list->id])) {
             foreach($form_state['values']['interest_groups_' . $list->id] as $key => $group) {
-              $merge_vars['GROUPINGS'][] = array('id' => $key, 'groups' => is_array($group) ? implode(', ', array_filter($group)) : $group);
+              $merge_vars['GROUPINGS'][] = array('id' => $key, 'groups' => $q->implodeInterestGroups($group));
             }
           }
 
@@ -520,28 +520,30 @@
  * @param <type> $q - MC API object
  */
 function mailchimp_subscribe_anon_form_submit($form, &$form_state) {
-  $lists = $form_state['values']['mailchimp_lists'];
-  foreach ($lists as $list) {
-    if (!empty($list['EMAIL'])) {
-      $success = FALSE;
+  if ($q = _mailchimp_get_api_object()) {
+    $lists = $form_state['values']['mailchimp_lists'];
+    foreach ($lists as $list) {
+      if (!empty($list['EMAIL'])) {
+        $success = FALSE;
 
-      // include interest groups
-      if (isset($list['interest_groups_' . $list['list']->id]) && is_array($list['interest_groups_' . $list['list']->id])) {
-        foreach($list['interest_groups_' . $list['list']->id] as $key => $group) {
-          $list['GROUPINGS'][] = array('id' => $key, 'groups' => is_array($group) ? implode(', ', array_filter($group)) : $group);
+        // include interest groups
+        if (isset($list['interest_groups_' . $list['list']->id]) && is_array($list['interest_groups_' . $list['list']->id])) {
+          foreach($list['interest_groups_' . $list['list']->id] as $key => $group) {
+            $list['GROUPINGS'][] = array('id' => $key, 'groups' => $q->implodeInterestGroups($group));
+          }
         }
-      }
 
-      $success = _mailchimp_subscribe_user($list['list'], $list['EMAIL'], $list, TRUE);
+        $success = _mailchimp_subscribe_user($list['list'], $list['EMAIL'], $list, TRUE, $q);
 
-      if ($success) {
-        $msg = t(variable_get('mailchimp_subscription_success_message', 'Thank you, you have been successfully subscribed.'));        
-      }
-      else {
-        $msg = t(variable_get('mailchimp_subscription_failure_message', 'We were unable to subscribe you at this time. Please try again later.'));        
-      }
+        if ($success) {
+          $msg = t(variable_get('mailchimp_subscription_success_message', 'Thank you, you have been successfully subscribed.'));        
+        }
+        else {
+          $msg = t(variable_get('mailchimp_subscription_failure_message', 'We were unable to subscribe you at this time. Please try again later.'));        
+        }
 
-      drupal_set_message($msg);
+        drupal_set_message($msg);
+      }
     }
   }
 }
@@ -666,7 +668,7 @@
         if (!empty($groupings)) {
           foreach($groupings as $grouping) {
             if ($grouping['id'] == $group['id']) {
-              $default = explode(",", str_replace(', ', ',', $grouping['groups']));
+              $default = $q->explodeInterestGroups($grouping['groups']);
             }
           }
         }
diff -ruN original/MCAPI.class.php mod/MCAPI.class.php
--- original/MCAPI.class.php	2011-04-28 01:13:47.000000000 +0700
+++ mod/MCAPI.class.php	2011-06-18 17:25:18.000000000 +0700
@@ -59,6 +59,43 @@
     }
     
     /**
+     * Escape commas in interest groups and implode if there are multiple
+     * values.
+     * 
+     * @param mixed $groups string with single group or array with groups
+     * @return string
+     */
+    function implodeInterestGroups($groups) {
+      if (!is_array($groups)) {
+        $groups = array($groups);
+      }
+      else {
+        $groups = array_filter($groups);
+      }
+      foreach ($groups as $key => $group) {
+        $groups[$key] = str_replace(',', '\,', $group);
+      }
+      $groups = implode(',', $groups);
+      return $groups;
+    }
+    
+    /**
+     * Parses interest groups into array and un-escapes commas in group names.
+     * 
+     * @param string $groups
+     * @return array
+     */
+    function explodeInterestGroups($groups) {
+      // Split by comma that is not preceded by backslash and followed by
+      // zero to one space
+      $groups = preg_split('/(?<!\\\\)\,\s?/', $groups);
+      foreach ($groups as $key => $group) {
+        $groups[$key] = str_replace('\,', ',', $group);
+      }
+      return $groups;
+    }
+    
+    /**
      * Unschedule a campaign that is scheduled to be sent in the future
      *
      * @section Campaign  Related