Text for email address validation!
Provide direct, simple feedback that people can understand. For example, error messages should spell out exactly what situation caused the error (“There’s not enough space on that disk to save the document”) and possible actions the user can take to rectify it (“Try saving the document in another location”).
Effective error messages inform users that a problem occurred, explain why it happened, and provide a solution so users can fix the problem. Users should either perform an action or change their behavior as the result of an error message.
which, to me, makes a lot of sense... so i'd go with something like "Invalid email address. Valid e-mail can contain only latin letters, numbers, '@' and '.'", or something more appropriate to your validations...