email generation generates invalid emails

Currently, emails for sample data seem to be generated by excluding spaces from the names of the contacts. This ends in addresses like mi?dzynarodowetargi?ódzkie@npo.edu, which are invalid, which ? in turn ? makes editing the contact without fixing the address impossible.

Note: this is different from CRM-40 (email validation being too restrictive); lodz@?ód?.pl is a vaild email address (although currently not allowed in CiviCRM), ?ód?@lodz.pl is not valid by any standard.