diff --git a/externals/phpmailer/class.phpmailer-lite.php b/externals/phpmailer/class.phpmailer-lite.php
--- a/externals/phpmailer/class.phpmailer-lite.php
+++ b/externals/phpmailer/class.phpmailer-lite.php
@@ -654,7 +654,7 @@
     $to = implode(', ', $toArr);
 
     $params = sprintf("-oi -f %s", $this->Sender);
-    if ($this->Sender != '' && strlen(ini_get('safe_mode'))< 1) {
+    if ($this->Sender != '') {
       $old_from = ini_get('sendmail_from');
       ini_set('sendmail_from', $this->Sender);
       if ($this->SingleTo === true && count($toArr) > 1) {
diff --git a/externals/phpmailer/class.phpmailer.php b/externals/phpmailer/class.phpmailer.php
--- a/externals/phpmailer/class.phpmailer.php
+++ b/externals/phpmailer/class.phpmailer.php
@@ -633,7 +633,7 @@
     $to = implode(', ', $toArr);
 
     $params = sprintf("-oi -f %s", $this->Sender);
-    if ($this->Sender != '' && strlen(ini_get('safe_mode'))< 1) {
+    if ($this->Sender != '') {
       $old_from = ini_get('sendmail_from');
       ini_set('sendmail_from', $this->Sender);
       if ($this->SingleTo === true && count($toArr) > 1) {
diff --git a/src/applications/config/check/PhabricatorPHPPreflightSetupCheck.php b/src/applications/config/check/PhabricatorPHPPreflightSetupCheck.php
--- a/src/applications/config/check/PhabricatorPHPPreflightSetupCheck.php
+++ b/src/applications/config/check/PhabricatorPHPPreflightSetupCheck.php
@@ -36,25 +36,6 @@
       return;
     }
 
-    // TODO: This can be removed entirely because the minimum PHP version is
-    // now PHP 5.5, which does not have safe mode.
-
-    $safe_mode = ini_get('safe_mode');
-    if ($safe_mode) {
-      $message = pht(
-        "You have '%s' enabled in your PHP configuration, but this software ".
-        "will not run in safe mode. Safe mode has been deprecated in PHP 5.3 ".
-        "and removed in PHP 5.4.\n\nDisable safe mode to continue.",
-        'safe_mode');
-
-      $this->newIssue('php.safe_mode')
-        ->setIsFatal(true)
-        ->setName(pht('Disable PHP %s', 'safe_mode'))
-        ->setMessage($message)
-        ->addPHPConfig('safe_mode');
-      return;
-    }
-
     // Check for `disable_functions` or `disable_classes`. Although it's
     // possible to disable a bunch of functions (say, `array_change_key_case()`)
     // and classes and still have Phabricator work fine, it's unreasonably