ERROR: Illegal character in domain
javax.mail.internet.AddressException: Illegal character in domain in string
This happens when the username is already a valid email

``heiko.braun@jboss.com@jboss.com''
at javax.mail.internet.InternetAddress.checkAddress(InternetAddress.java:933)
at javax.mail.internet.InternetAddress.parse(InternetAddress.java:819)
at javax.mail.internet.InternetAddress.parse(InternetAddress.java:555)
at javax.mail.internet.InternetAddress.<init>(InternetAddress.java:91)
at hudson.tasks.MailSender.createEmptyMail(MailSender.java:252)
at hudson.tasks.MailSender.createFailureMail(MailSender.java:143)
at hudson.tasks.MailSender.getMail(MailSender.java:87)
at hudson.tasks.MailSender.execute(MailSender.java:64)
at hudson.tasks.Mailer.perform(Mailer.java:61)