Redmine

The issue can be fixed if the regular expression is changed as follows:

diff --git a/app/models/email_address.rb b/app/models/email_address.rb
index 46bca384a..dd0b30607 100644
--- a/app/models/email_address.rb
+++ b/app/models/email_address.rb
@@ -20,7 +20,7 @@
 class EmailAddress < ActiveRecord::Base
   include Redmine::SafeAttributes

-  EMAIL_REGEXP = /\A([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})\z/i
+  EMAIL_REGEXP = /\A([^@\s]+)@((?:[-a-z0-9]+\.)+(?:(?:xn--[-a-z0-9]+)|(?:[a-z]{2,})))\z/i

   belongs_to :user