diff --git a/composer.json b/composer.json
index a02a534..fe4ce05 100644
--- a/composer.json
+++ b/composer.json
@@ -16,7 +16,7 @@
     }
   ],
   "require": {
-    "php": "~5.6.0|~7.0.17",
+    "php": "~5.6.0|~7.1.20",
     "x59/horde-mime": "~2.9.5",
     "x59/horde-util": "~2.5.7",
     "pear-pear.php.net/Mail_mimeDecode": "~1.5.6"
diff --git a/src/Client.php b/src/Client.php
index 3720916..6898ad5 100644
--- a/src/Client.php
+++ b/src/Client.php
@@ -48,6 +48,7 @@ public function sendRequest($request) {
             CURLOPT_URL            => $request->getUrl(),
             CURLOPT_HEADER         => false,
             CURLOPT_HTTPHEADER     => $headers,
+            CURLOPT_INTERFACE      => AS2_IP,
             CURLOPT_RETURNTRANSFER => true,
             CURLOPT_BINARYTRANSFER => true,
             CURLOPT_FOLLOWLOCATION => true,
@@ -80,4 +81,4 @@ public function sendRequest($request) {
 
         return $this;
     }
-}
\ No newline at end of file
+}