diff --git a/src/main/groovy/org/jenkinsci/plugins/pollmailboxtrigger/mail/utils/Stringify.java b/src/main/groovy/org/jenkinsci/plugins/pollmailboxtrigger/mail/utils/Stringify.java
index 1a655bd..45c4e79 100644
--- a/src/main/groovy/org/jenkinsci/plugins/pollmailboxtrigger/mail/utils/Stringify.java
+++ b/src/main/groovy/org/jenkinsci/plugins/pollmailboxtrigger/mail/utils/Stringify.java
@@ -302,15 +302,18 @@ public static String stringify(final Header content) {
      * @return a String
      */
     public static String stringify(final Address[] addresses) {
-        List<String> parsed = new ArrayList<String>();
-        for (Address addr : addresses) {
-            if (addr instanceof InternetAddress) {
-                parsed.add(((InternetAddress) addr).getAddress());
-            } else {
-                parsed.add(addr.toString());
+        if (addresses != null) {
+            List<String> parsed = new ArrayList<String>();
+            for (Address addr : addresses) {
+                if (addr instanceof InternetAddress) {
+                    parsed.add(((InternetAddress) addr).getAddress());
+                } else {
+                    parsed.add(addr.toString());
+                }
             }
+            return StringUtils.join(parsed, ",");
         }
-        return StringUtils.join(parsed, ",");
+        return "";
     }
 
     /**
@@ -402,4 +405,4 @@ public static String stringify(final Folder folder) {
         return folder.getFullName();
     }
 
-}
\ No newline at end of file
+}