diff -u b/includes/mail.inc b/includes/mail.inc
--- b/includes/mail.inc
+++ b/includes/mail.inc
@@ -249,100 +249,68 @@
     }
   }
 
-  // Retrieve list of users being globally subscribed to all issues.
-  $accounts_all_issues = array();
-  $result = db_query("SELECT pisu.uid, u.name, u.mail FROM {project_issue_subscriptions_user} pisu INNER JOIN {users} u ON pisu.uid = u.uid WHERE u.status = 1 AND pisu.level = " . PROJECT_ISSUE_SUBSCRIPTIONS_ALL);
-  while ($account = db_fetch_object($result)) {
-    $accounts_all_issues[$account->uid] = $account;
-  }
-
   // Check whether Flag module integration is enabled for e-mail notifications.
   $flag_integration = (module_exists('flag') && variable_get('project_issue_subscription_flag', 0));
 
-  // Retrieve list of users being globally subscribed to "own" issues (without
-  // Flag integration).
-  $accounts_flagged_issues = array();
-  if (!$flag_integration) {
-    $result = db_query("SELECT pisu.uid, u.name, u.mail FROM {project_issue_subscriptions_user} pisu INNER JOIN {users} u ON pisu.uid = u.uid WHERE u.status = 1 AND pisu.level = " . PROJECT_ISSUE_SUBSCRIPTIONS_FLAGGED);
-    while ($account = db_fetch_object($result)) {
-      $accounts_flagged_issues[$account->uid] = $account;
-    }
+  // If flag integration is present, the list of users for 'own' issues will
+  // be those that flagged the issue.
+  if ($flag_integration) {
+    // Retrieve all users who flagged the issue.
+    $flag_contents = flag_get_content_flags('node', $node->nid, variable_get('project_issue_subscription_flag', 0));
+    $own_issues_uids = array_keys($flag_contents);
+  }
+  // Without flag integration, 'own issues' are all users that posted to the
+  // issue.
+  else {
+    $own_issues_uids = array_keys($uids);
   }
 
-  // Check per-project subscriptions of involved users.
-  if (!empty($uids)) {
-    $placeholders = implode(',', array_fill(0, count($uids), '%d'));
-    $args = $uids;
-    array_unshift($args, $node->project_issue['pid']);
-
-    // Check which involved users are subscribed to all issues of the project.
-    $result = db_query("SELECT pisp.uid, u.name, u.mail
-      FROM {project_issue_subscriptions_project} pisp
-      INNER JOIN {users} u ON pisp.uid = u.uid
-      WHERE u.status = 1 AND pisp.nid = %d AND pisp.uid IN ($placeholders) AND pisp.level = " . PROJECT_ISSUE_SUBSCRIPTIONS_ALL, $args);
-    while ($account = db_fetch_object($result)) {
-      $accounts_all_issues[$account->uid] = $account;
-    }
 
-    // Check which involved users are subscribed to "own" issues of the project
-    // (without Flag integration).
-    if (!$flag_integration) {
-      $result = db_query("SELECT pisp.uid, u.name, u.mail
-        FROM {project_issue_subscriptions_project} pisp
-        INNER JOIN {users} u ON pisp.uid = u.uid
-        WHERE u.status = 1 AND pisp.nid = %d AND pisp.uid IN ($placeholders) AND pisp.level = " . PROJECT_ISSUE_SUBSCRIPTIONS_FLAGGED, $args);
-      while ($account = db_fetch_object($result)) {
-        $accounts_flagged_issues[$account->uid] = $account;
-      }
-    }
+  // Initialize the recipient list.  After compilation, the list will include
+  // users that are:
+  //  - globally subscribed to all issues
+  //  - globally subscribed to own issues (without Flag integration)
+  //  - globally subscribed to flagged issues
+  //  - subscribed to all issues of the project
+  //  - subscribed to own issues of the project (without Flag integration)
+  //  - subscribed to flagged issues of the project
+  $recipients = array();
+
+  $args = array();
+
+  // Build up filters for different issue subscription levels.
+  $filter_array = array();
+  // 'All' level.
+  $filter_array[] = "(pi.level = " . PROJECT_ISSUE_SUBSCRIPTIONS_ALL . ")";
+  // 'Own' level using the list of users attached to the issue.
+  if (!empty($own_issues_uids)) {
+    $placeholders = implode(',', array_fill(0, count($own_issues_uids), '%d'));
+    $filter_array[] = "(pi.uid IN ($placeholders) AND pi.level = " . PROJECT_ISSUE_SUBSCRIPTIONS_FLAGGED . ")";
+    $args = array_merge($args, $own_issues_uids);
   }
+  $filter = implode(" OR ", $filter_array);
 
-  // Check which users subscribed to the issue via Flag.
-  if ($flag_integration) {
-    // Retrieve all users who flagged the issue.
-    $flag_contents = flag_get_content_flags('node', $node->nid, variable_get('project_issue_subscription_flag', 0));
-
-    // Now use the list of users that flagged the issue to retrieve the list of
-    // users who are subscribed to flagged issues of the project. For example, a
-    // user who globally subscribed to no issues should not get an e-mail
-    // notification after flagging the issue. That should only happen when the
-    // user subscribed to flagged issues for the project.
-    if (!empty($flag_contents)) {
-      $flags_uids = array_keys($flag_contents);
-      $placeholders = implode(',', array_fill(0, count($flags_uids), '%d'));
-      $args = $flags_uids;
-
-      // Check which users flagged the issue and globally subscribed to flagged
-      // issues (across projects).
-      $result = db_query("SELECT pisu.uid, u.name, u.mail
-        FROM {project_issue_subscriptions_user} pisu
-        INNER JOIN {users} u ON pisu.uid = u.uid
-        WHERE u.status = 1 AND pisu.uid IN ($placeholders) AND pisu.level = " . PROJECT_ISSUE_SUBSCRIPTIONS_FLAGGED, $args);
-      while ($account = db_fetch_object($result)) {
-        $accounts_flagged_issues[$account->uid] = $account;
-      }
-
-      // Check which users flagged the issue and subscribed to flagged issues of
-      // the project.
-      array_unshift($args, $node->project_issue['pid']);
-      $result = db_query("SELECT pisp.uid, u.name, u.mail
-        FROM {project_issue_subscriptions_project} pisp
-        INNER JOIN {users} u ON pisp.uid = u.uid
-        WHERE u.status = 1 AND pisp.nid = %d AND pisp.uid IN ($placeholders) AND pisp.level = " . PROJECT_ISSUE_SUBSCRIPTIONS_FLAGGED, $args);
-      while ($account = db_fetch_object($result)) {
-        $accounts_flagged_issues[$account->uid] = $account;
-      }
-    }
+  // Pull subscribers at the user level.
+  $user_levels_query = "SELECT pi.uid, u.name, u.mail
+    FROM {project_issue_subscriptions_user} pi
+    INNER JOIN {users} u ON pi.uid = u.uid
+    WHERE u.status = 1 AND (" . $filter . ")";
+  $result = db_query($user_levels_query, $args);
+  while ($account = db_fetch_object($result)) {
+    $recipients[$account->uid] = $account;
   }
 
-  // Lastly, join the lists of users being
-  // - globally subscribed to all issues
-  // - globally subscribed to own issues (without Flag integration)
-  // - globally subscribed to flagged issues
-  // - subscribed to all issues of the project
-  // - subscribed to own issues of the project (without Flag integration)
-  // - subscribed to flagged issues of the project
-  $recipients = $accounts_all_issues + $accounts_flagged_issues;
+  // Pull subscribers at the project level.
+  $project_levels_query = "SELECT pi.uid, u.name, u.mail
+    FROM {project_issue_subscriptions_project} pi
+    INNER JOIN {users} u ON pi.uid = u.uid
+    WHERE u.status = 1 AND pi.nid = %d AND (" . $filter . ")";
+  $project_levels_args = $args;
+  array_unshift($project_levels_args, $node->project_issue['pid']);
+  $result = db_query($project_levels_query, $project_levels_args);
+  while ($account = db_fetch_object($result)) {
+    $recipients[$account->uid] = $account;
+  }
 
   // To save workload, check here if either the anonymous role or the
   // authenticated role has the 'view uploaded files' permission, since