LEA are not alone in this practice, which is not illegal.
No one is suggesting the e mails themselves were illegal.....but using them in substitution for reporting matters that should have been recorded and were not certainly is.
Read page 21 of the report.
57 items (!!) that either required immediate rectification or deferal in accordance with MEL for either three or ten days were not properly entered in the tech log in the preceding nine months!!! The report observes that the aircraft was flown with essential maintenance items outstanding because of this.
The first job of a competent Captain on entering the flight deck pre-flight is to read the tech log and check , amongst other matters, the engineering status of the aircraft including the status of any deferred defects. He is entitled to rely on that as the definitive source of information as to the status of the aircraft ( apart from anything he observes from his own pre flight checks)not wade through a stream of company e mails.....