[FIXED JENKINS-10300] Empty emailAddress causes Mailer error.

changelog.html

@@ -66,6 +66,9 @@ Upcoming changes</a>
   <li class=bug>
     ToolCommandInstaller: Fix CR/LF and always make it Unix style.
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-9963">issue 9963</a>)
+  <li class=bug>
+    Empty emailAddress causes Mailer error.
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-10300">issue 10300</a>)
   <li class=rfe>
     PAM authentication now works with CLI login mechanism.
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-9681">issue 9681</a>)

core/src/main/java/hudson/tasks/Mailer.java

@@ -478,7 +478,7 @@ public class Mailer extends Notifier {
 
         @Exported
         public String getAddress() {
-            if(emailAddress!=null)
+            if(Util.fixEmptyAndTrim(emailAddress)!=null)
                 return emailAddress;
 
             // try the inference logic