fix: fix user email incorrect format

[stanislavefremov]

sendMailToUser function gets email body in $post_body variable and unconditionally applies htmlspecialchars to it, which escapes html tags. It maybe unneeded as later sendMailToUser passes email body to $emailService->sendMail method which performs XSS check through sanitizeEmailBody method and applies htmlspecialchars if needed.

[stanislavefremov]

htmlspecialchars in sendMailToUser function seems to be unnecessary. PR suggested as a solution for ##4482 issue

[corentin-soriano]

It seems to me that this function is used by mail_me (direct user input). I think wee can add $antiXSS->clean() to clear eventual XSS payload without break the html.