When SSPI authentication is used for SVN, the username Hudson sees is in the form of "DOMAIN\user". If the "Default user e-mail suffix" property has been configured to "company.com", the MailAddressResolver comes up with an email address in the form of "DOMAIN_user@company.com".

It would be ideal if the MailAddressResolver could strip out any text up to and including a backslash in the user's SCM ID when trying to come up with a fallback address, as leaving it in (even with an underscore) will never be the correct behavior.