Address test.töst@test.com is not valid MailerBuilder.clearEmailAddressCriteria() doesn't play any role because org.hazlewood.connor.bottema.emailaddress.EmailAddressValidator#isValidMailbox still return false Just change email to test.tost@test.com it became valid. Using RFC strategy also is not working. According to the latest RFC UTF-8 is valid to be used in emails.