Assign Invalid will be used to create an email for subscribers with an invalid email address. You can use values between [ and ] to make up a value for the email. For example if your import file contains a column \"First Name\" and one called \"Last Name\", you can use \"[first name] [last name]\" to construct a new value for the email for this subscriber containing their first name and last name. The value [number] can be used to insert the sequence number for importing.