Use strict email address validation in SendEmailUtils

It probably should have always been like this, but the Nomulus test recently
started failing without it for some reason.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=144343479

java/google/registry/ui/server/registrar/SendEmailUtils.java

@@ -66,7 +66,7 @@ public class SendEmailUtils {
             @Override
             public InternetAddress apply(String emailAddress) {
               try {
-                return new InternetAddress(emailAddress);
+                return new InternetAddress(emailAddress, true);
               } catch (AddressException e) {
                 logger.severefmt(
                     e,